diff --git a/Core/GDCore/IDE/WholeProjectRefactorer.cpp b/Core/GDCore/IDE/WholeProjectRefactorer.cpp
index b732d71ef..0ba5cbb4d 100644
--- a/Core/GDCore/IDE/WholeProjectRefactorer.cpp
+++ b/Core/GDCore/IDE/WholeProjectRefactorer.cpp
@@ -1032,6 +1032,8 @@ void WholeProjectRefactorer::RenameEventsBasedBehaviorProperty(
       behaviorType, oldPropertyName, newPropertyName);
   projectBrowser.ExposeObjects(project, behaviorPropertyRenamer);
 
+  // TODO Rename the property in behavior overridings of InitialInstances.
+
   if (properties.Get(oldPropertyName).GetType() == "Behavior") {
     // This is a property representing another behavior that must exist on the
     // object.
diff --git a/Core/GDCore/Project/BehaviorConfigurationContainer.cpp b/Core/GDCore/Project/BehaviorConfigurationContainer.cpp
index 9dea002cc..4afbf5cde 100644
--- a/Core/GDCore/Project/BehaviorConfigurationContainer.cpp
+++ b/Core/GDCore/Project/BehaviorConfigurationContainer.cpp
@@ -14,8 +14,8 @@ BehaviorConfigurationContainer::~BehaviorConfigurationContainer(){};
 
 
 std::map<gd::String, gd::PropertyDescriptor> BehaviorConfigurationContainer::GetProperties() const {
-    return GetProperties(content);
-  };
+  return GetProperties(content);
+}
 
 std::map<gd::String, gd::PropertyDescriptor> BehaviorConfigurationContainer::GetProperties(
     const gd::SerializerElement& behaviorContent) const {
diff --git a/Core/GDCore/Project/BehaviorConfigurationContainer.h b/Core/GDCore/Project/BehaviorConfigurationContainer.h
index a3e70d93e..8d43dd12f 100644
--- a/Core/GDCore/Project/BehaviorConfigurationContainer.h
+++ b/Core/GDCore/Project/BehaviorConfigurationContainer.h
@@ -81,7 +81,6 @@ class GD_CORE_API BehaviorConfigurationContainer {
    * behavior
    *
    * \return false if the new value cannot be set
-   * \see gd::InitialInstance
    */
   bool UpdateProperty(const gd::String& name, const gd::String& value) {
     return UpdateProperty(content, name, value);
@@ -98,11 +97,42 @@ class GD_CORE_API BehaviorConfigurationContainer {
     return RenameProperty(content, oldName, newName);
   };
 
+  /**
+   * \brief Called when the IDE wants to remove a custom property from the
+   * behavior
+   *
+   * \see gd::InitialInstance
+   */
+  void RemoveProperty(const gd::String &name) {
+    content.RemoveChild(name);
+    content.RemoveAttribute(name);
+  };
+
+  /**
+   * \brief Called to check if a property is overriden.
+   *
+   * \see gd::InitialInstance
+   */
+  bool HasPropertyValue(const gd::String name) const {
+    return content.HasChild(name) || content.HasAttribute(name);
+  }
+
   /**
    * \brief Called to initialize the content with the default properties
    * for the behavior.
    */
-  virtual void InitializeContent() { InitializeContent(content); };
+  virtual void InitializeContent() {
+    InitializeContent(content);
+  };
+
+  /**
+   * \brief Called to remove all properties values for the behavior.
+   * 
+   * \see gd::InitialInstance
+   */
+  void ClearContent() {
+    content.Clear();
+  };
 
   /**
    * \brief Serialize the behavior content.
@@ -202,7 +232,6 @@ class GD_CORE_API BehaviorConfigurationContainer {
    * behavior
    *
    * \return false if the new value cannot be set
-   * \see gd::InitialInstance
    */
   virtual bool UpdateProperty(gd::SerializerElement& behaviorContent,
                               const gd::String& name,
diff --git a/Core/GDCore/Project/BehaviorsContainer.cpp b/Core/GDCore/Project/BehaviorsContainer.cpp
new file mode 100644
index 000000000..a9e70b1e1
--- /dev/null
+++ b/Core/GDCore/Project/BehaviorsContainer.cpp
@@ -0,0 +1,205 @@
+/*
+ * GDevelop Core
+ * Copyright 2008-2016 Florian Rival (Florian.Rival@gmail.com). All rights
+ * reserved. This project is released under the MIT License.
+ */
+#include "GDCore/Project/BehaviorsContainer.h"
+
+#include "GDCore/Extensions/Metadata/BehaviorMetadata.h"
+#include "GDCore/Extensions/Metadata/MetadataProvider.h"
+#include "GDCore/Extensions/Platform.h"
+#include "GDCore/Project/Behavior.h"
+#include "GDCore/Project/CustomBehavior.h"
+#include "GDCore/Project/Project.h"
+#include "GDCore/Project/PropertyDescriptor.h"
+#include "GDCore/Project/QuickCustomization.h"
+#include "GDCore/Serialization/SerializerElement.h"
+#include "GDCore/Tools/Log.h"
+#include "GDCore/Tools/UUID/UUID.h"
+
+namespace gd {
+
+BehaviorsContainer::~BehaviorsContainer() {}
+
+BehaviorsContainer::BehaviorsContainer(bool isOverriding_)
+    : isOverriding(isOverriding_) {}
+
+void BehaviorsContainer::Init(const gd::BehaviorsContainer &behaviorsContainer) {
+  isOverriding = behaviorsContainer.isOverriding;
+  behaviors = gd::Clone(behaviorsContainer.behaviors);
+}
+
+std::vector<gd::String> BehaviorsContainer::GetAllBehaviorNames() const {
+  std::vector<gd::String> allNameIdentifiers;
+
+  for (auto &it : behaviors)
+    allNameIdentifiers.push_back(it.first);
+
+  return allNameIdentifiers;
+}
+
+void BehaviorsContainer::RemoveBehavior(const gd::String &name) {
+  behaviors.erase(name);
+}
+
+bool BehaviorsContainer::RenameBehavior(const gd::String &name,
+                                        const gd::String &newName) {
+  if (behaviors.find(name) == behaviors.end() ||
+      behaviors.find(newName) != behaviors.end())
+    return false;
+
+  std::unique_ptr<Behavior> aut = std::move(behaviors.find(name)->second);
+  behaviors.erase(name);
+  behaviors[newName] = std::move(aut);
+  behaviors[newName]->SetName(newName);
+
+  return true;
+}
+
+gd::Behavior &BehaviorsContainer::GetBehavior(const gd::String &name) {
+  return *behaviors.find(name)->second;
+}
+
+const gd::Behavior &
+BehaviorsContainer::GetBehavior(const gd::String &name) const {
+  return *behaviors.find(name)->second;
+}
+
+bool BehaviorsContainer::HasBehaviorNamed(const gd::String &name) const {
+  return behaviors.find(name) != behaviors.end();
+}
+
+gd::Behavior *BehaviorsContainer::AddNewBehavior(const gd::Project &project,
+                                                 const gd::String &type,
+                                                 const gd::String &name) {
+  auto initializeAndAdd = [this,
+                           &name](std::unique_ptr<gd::Behavior> behavior) {
+    if (isOverriding) {
+      // We don't call the Initialize method for behavior overridings because they
+      // should have no property value initially.
+      behavior->ClearContent();
+    }
+    else {
+      behavior->InitializeContent();
+    }
+    this->behaviors[name] = std::move(behavior);
+    return this->behaviors[name].get();
+  };
+
+  if (project.HasEventsBasedBehavior(type)) {
+    return initializeAndAdd(
+        gd::make_unique<CustomBehavior>(name, project, type));
+  } else {
+    const gd::BehaviorMetadata &behaviorMetadata =
+        gd::MetadataProvider::GetBehaviorMetadata(project.GetCurrentPlatform(),
+                                                  type);
+    if (gd::MetadataProvider::IsBadBehaviorMetadata(behaviorMetadata)) {
+      gd::LogWarning("Tried to create a behavior with an unknown type: " +
+                     type);
+      // It's probably an events-based behavior that was removed.
+      // Create a custom behavior to preserve the properties values.
+      return initializeAndAdd(
+          gd::make_unique<CustomBehavior>(name, project, type));
+    }
+    std::unique_ptr<gd::Behavior> behavior(behaviorMetadata.Get().Clone());
+    behavior->SetName(name);
+    return initializeAndAdd(std::move(behavior));
+  }
+}
+
+void BehaviorsContainer::UnserializeFrom(gd::Project &project,
+                                         const SerializerElement &element) {
+  element.ConsiderAsArrayOf("behavior", "automatism");
+  for (std::size_t i = 0; i < element.GetChildrenCount(); ++i) {
+    SerializerElement &behaviorElement = element.GetChild(i);
+
+    gd::String type = behaviorElement.GetStringAttribute("type").FindAndReplace(
+        "Automatism", "Behavior"); // Compatibility with GD <= 4
+    gd::String name = behaviorElement.GetStringAttribute("name");
+
+    auto behavior = gd::BehaviorsContainer::AddNewBehavior(project, type, name);
+    // Compatibility with GD <= 4.0.98
+    // If there is only one child called "content" (in addition to "type" and
+    // "name"), it's the content of a JavaScript behavior. Move the content
+    // out of the "content" object (to put it directly at the root of the
+    // behavior element).
+    if (behaviorElement.HasChild("content") &&
+        behaviorElement.GetAllChildren().size() == 3) {
+      SerializerElement &contentElement = behaviorElement.GetChild("content");
+
+      // Physics2 Behavior was using "type" for the type of the body. The name
+      // conflicts with the behavior "type". Rename it.
+      if (contentElement.HasChild("type")) {
+        contentElement.AddChild("bodyType")
+            .SetValue(contentElement.GetChild("type").GetStringValue());
+        contentElement.RemoveChild("type");
+      }
+
+      behavior->UnserializeFrom(contentElement);
+    }
+    // end of compatibility code
+    else {
+      behavior->UnserializeFrom(behaviorElement);
+    }
+
+    bool isFolded = behaviorElement.GetBoolAttribute("isFolded", false);
+    behavior->SetFolded(isFolded);
+
+    // Handle Quick Customization info.
+    if (behaviorElement.HasChild("propertiesQuickCustomizationVisibilities")) {
+      behavior->GetPropertiesQuickCustomizationVisibilities().UnserializeFrom(
+          behaviorElement.GetChild("propertiesQuickCustomizationVisibilities"));
+    }
+    if (behaviorElement.HasChild("quickCustomizationVisibility")) {
+      behavior->SetQuickCustomizationVisibility(
+          QuickCustomization::StringAsVisibility(
+              behaviorElement.GetStringAttribute(
+                  "quickCustomizationVisibility")));
+    }
+  }
+}
+
+void BehaviorsContainer::SerializeTo(SerializerElement &element) const {
+  element.ConsiderAsArrayOf("behavior");
+  std::vector<gd::String> allBehaviors = GetAllBehaviorNames();
+  for (std::size_t i = 0; i < allBehaviors.size(); ++i) {
+    const gd::Behavior &behavior = GetBehavior(allBehaviors[i]);
+    // Default behaviors are added at the object creation according to
+    // metadata. They don't need to be serialized.
+    // During the export, all behaviors are set as not default by
+    // `BehaviorDefaultFlagClearer` because the Runtime needs all the behaviors.
+    if (behavior.IsDefaultBehavior()) {
+      continue;
+    }
+    SerializerElement &behaviorElement = element.AddChild("behavior");
+
+    behavior.SerializeTo(behaviorElement);
+    behaviorElement.RemoveChild("type"); // The content can contain type or
+                                         // name properties, remove them.
+    behaviorElement.RemoveChild("name");
+    behaviorElement.RemoveChild("isFolded");
+    behaviorElement.SetAttribute("type", behavior.GetTypeName());
+    behaviorElement.SetAttribute("name", behavior.GetName());
+    if (behavior.IsFolded())
+      behaviorElement.SetAttribute("isFolded", true);
+
+    // Handle Quick Customization info.
+    behaviorElement.RemoveChild("propertiesQuickCustomizationVisibilities");
+    const QuickCustomizationVisibilitiesContainer
+        &propertiesQuickCustomizationVisibilities =
+            behavior.GetPropertiesQuickCustomizationVisibilities();
+    if (!propertiesQuickCustomizationVisibilities.IsEmpty()) {
+      propertiesQuickCustomizationVisibilities.SerializeTo(
+          behaviorElement.AddChild("propertiesQuickCustomizationVisibilities"));
+    }
+    const QuickCustomization::Visibility visibility =
+        behavior.GetQuickCustomizationVisibility();
+    if (visibility != QuickCustomization::Visibility::Default) {
+      behaviorElement.SetAttribute(
+          "quickCustomizationVisibility",
+          QuickCustomization::VisibilityAsString(visibility));
+    }
+  }
+}
+
+} // namespace gd
diff --git a/Core/GDCore/Project/BehaviorsContainer.h b/Core/GDCore/Project/BehaviorsContainer.h
new file mode 100644
index 000000000..4954ab475
--- /dev/null
+++ b/Core/GDCore/Project/BehaviorsContainer.h
@@ -0,0 +1,158 @@
+/*
+ * GDevelop Core
+ * Copyright 2008-2016 Florian Rival (Florian.Rival@gmail.com). All rights
+ * reserved. This project is released under the MIT License.
+ */
+#pragma once
+
+#include <map>
+#include <memory>
+#include <vector>
+
+#include "GDCore/Project/Behavior.h"
+#include "GDCore/Project/EffectsContainer.h"
+#include "GDCore/Project/ObjectConfiguration.h"
+#include "GDCore/Project/VariablesContainer.h"
+#include "GDCore/String.h"
+#include "GDCore/Tools/MakeUnique.h"
+#include "GDCore/Vector2.h"
+
+namespace gd {
+class PropertyDescriptor;
+class Project;
+class Layout;
+class ArbitraryResourceWorker;
+class InitialInstance;
+class SerializerElement;
+class EffectsContainer;
+} // namespace gd
+
+namespace gd {
+
+/**
+ * \brief Represent an behaviors container of a platform
+ *
+ * \ingroup PlatformDefinition
+ */
+class GD_CORE_API BehaviorsContainer {
+public:
+  /**
+   * Create a new behaviors container with the name passed as argument.
+   */
+  BehaviorsContainer(bool isOverriding = false);
+
+  /**
+   * Copy constructor. Calls Init().
+   */
+  BehaviorsContainer(const gd::BehaviorsContainer &behaviorsContainer) {
+    Init(behaviorsContainer);
+  };
+
+  /**
+   * Assignment operator. Calls Init().
+   */
+  BehaviorsContainer &
+  operator=(const gd::BehaviorsContainer &behaviorsContainer) {
+    if ((this) != &behaviorsContainer)
+      Init(behaviorsContainer);
+    return *this;
+  }
+
+  /**
+   * Destructor.
+   */
+  virtual ~BehaviorsContainer();
+
+  /** \name Behaviors management
+   * Members functions related to behaviors management.
+   */
+  ///@{
+
+  /**
+   * \brief Return a vector containing the names of all the behaviors used by
+   * the behaviors container
+   */
+  std::vector<gd::String> GetAllBehaviorNames() const;
+
+  /**
+   * \brief Return a reference to the content of the behavior called \a name.
+   */
+  Behavior &GetBehavior(const gd::String &name);
+
+  /**
+   * \brief Return a reference to the content of the behavior called \a name.
+   */
+  const Behavior &GetBehavior(const gd::String &name) const;
+
+  /**
+   * \brief Return true if behaviors container has a behavior called \a name.
+   */
+  bool HasBehaviorNamed(const gd::String &name) const;
+
+  /**
+   * \brief Remove behavior called \a name
+   */
+  void RemoveBehavior(const gd::String &name);
+
+  /**
+   * \brief Change the name of behavior called name to newName.
+   * \return true if name was successfully changed
+   */
+  bool RenameBehavior(const gd::String &name, const gd::String &newName);
+
+  /**
+   * \brief Add the behavior of the specified \a type with the specified \a
+   * name.
+   *
+   * The project's current platform is used to initialize the content.
+   *
+   * \return A pointer to the newly added behavior content. NULL if the creation
+   * failed.
+   */
+  gd::Behavior *AddNewBehavior(const gd::Project &project,
+                               const gd::String &type, const gd::String &name);
+
+  /**
+   * \brief Get a read-only access to the map containing the behaviors with
+   * their properties.
+   */
+  const std::map<gd::String, std::unique_ptr<gd::Behavior>> &
+  GetAllBehaviorContents() const {
+    return behaviors;
+  };
+  ///@}
+
+  /** \name Serialization
+   * Members functions related to serialization of the behaviors container
+   */
+  ///@{
+  /**
+   * \brief Serialize the behaviors container.
+   * \see DoSerializeTo
+   */
+  void SerializeTo(SerializerElement &element) const;
+
+  /**
+   * \brief Unserialize the behaviors container.
+   * \see DoUnserializeFrom
+   */
+  void UnserializeFrom(gd::Project &project, const SerializerElement &element);
+
+protected:
+  bool isOverriding = false;
+  std::map<gd::String, std::unique_ptr<gd::Behavior>>
+      behaviors; ///< Contains all behaviors and their properties for the
+                 ///< behaviors container. Behavior contents are the ownership
+                 ///< of the behaviors container.
+
+  /**
+   * Initialize behaviors container using another behaviors container. Used by
+   * copy-ctor and assign-op. Don't forget to update me if members were changed!
+   *
+   * It's needed because there is no default copy for a map of unique_ptr like
+   * behaviors and it must be a deep copy.
+   */
+  void Init(const gd::BehaviorsContainer &behaviorsContainer);
+};
+
+} // namespace gd
diff --git a/Core/GDCore/Project/EventsBasedObjectVariant.cpp b/Core/GDCore/Project/EventsBasedObjectVariant.cpp
index a917912c3..2f3ba0e03 100644
--- a/Core/GDCore/Project/EventsBasedObjectVariant.cpp
+++ b/Core/GDCore/Project/EventsBasedObjectVariant.cpp
@@ -66,7 +66,7 @@ void EventsBasedObjectVariant::UnserializeFrom(
   } else {
     layers.Reset();
   }
-  initialInstances.UnserializeFrom(element.GetChild("instances"));
+  initialInstances.UnserializeFrom(project, element.GetChild("instances"));
   editorSettings.UnserializeFrom(element.GetChild("editionSettings"));
 }
 
diff --git a/Core/GDCore/Project/ExternalLayout.cpp b/Core/GDCore/Project/ExternalLayout.cpp
index a7a15781f..2da46ae3e 100644
--- a/Core/GDCore/Project/ExternalLayout.cpp
+++ b/Core/GDCore/Project/ExternalLayout.cpp
@@ -12,9 +12,10 @@
 
 namespace gd {
 
-void ExternalLayout::UnserializeFrom(const SerializerElement& element) {
+void ExternalLayout::UnserializeFrom(gd::Project &project,
+                                     const SerializerElement &element) {
   name = element.GetStringAttribute("name", "", "Name");
-  instances.UnserializeFrom(element.GetChild("instances", 0, "Instances"));
+  instances.UnserializeFrom(project, element.GetChild("instances", 0, "Instances"));
   editorSettings.UnserializeFrom(element.GetChild("editionSettings"));
   associatedLayout = element.GetStringAttribute("associatedLayout");
 }
diff --git a/Core/GDCore/Project/ExternalLayout.h b/Core/GDCore/Project/ExternalLayout.h
index 6c25db8f2..51b4a5752 100644
--- a/Core/GDCore/Project/ExternalLayout.h
+++ b/Core/GDCore/Project/ExternalLayout.h
@@ -4,8 +4,8 @@
  * reserved. This project is released under the MIT License.
  */
 
-#ifndef GDCORE_EXTERNALLAYOUT_H
-#define GDCORE_EXTERNALLAYOUT_H
+#pragma once
+
 #include <memory>
 
 #include "GDCore/Project/InitialInstancesContainer.h"
@@ -86,7 +86,7 @@ class GD_CORE_API ExternalLayout {
   /**
    * \brief Unserialize the external layout.
    */
-  void UnserializeFrom(const SerializerElement& element);
+  void UnserializeFrom(gd::Project &project, const SerializerElement& element);
   ///@}
 
  private:
@@ -98,4 +98,3 @@ class GD_CORE_API ExternalLayout {
 
 }  // namespace gd
 
-#endif  // GDCORE_EXTERNALLAYOUT_H
diff --git a/Core/GDCore/Project/InitialInstance.cpp b/Core/GDCore/Project/InitialInstance.cpp
index 3944bcc9e..589120a02 100644
--- a/Core/GDCore/Project/InitialInstance.cpp
+++ b/Core/GDCore/Project/InitialInstance.cpp
@@ -13,6 +13,10 @@
 #include "GDCore/Project/PropertyDescriptor.h"
 #include "GDCore/Serialization/SerializerElement.h"
 #include "GDCore/Tools/UUID/UUID.h"
+#include "GDCore/Extensions/Metadata/BehaviorMetadata.h"
+#include "GDCore/Extensions/Metadata/MetadataProvider.h"
+#include "GDCore/Project/CustomBehavior.h"
+#include "GDCore/Tools/Log.h"
 
 namespace gd {
 
@@ -20,29 +24,12 @@ gd::String* InitialInstance::badStringPropertyValue = NULL;
 
 InitialInstance::InitialInstance()
     : objectName(""),
-      x(0),
-      y(0),
-      z(0),
-      angle(0),
-      rotationX(0),
-      rotationY(0),
-      zOrder(0),
-      opacity(255),
       layer(""),
-      flippedX(false),
-      flippedY(false),
-      flippedZ(false),
-      customSize(false),
-      customDepth(false),
-      width(0),
-      height(0),
-      depth(0),
-      locked(false),
-      sealed(false),
-      keepRatio(true),
-      persistentUuid(UUID::MakeUuid4()) {}
+      persistentUuid(UUID::MakeUuid4()),
+      behaviorOverridings(true) {}
 
-void InitialInstance::UnserializeFrom(const SerializerElement& element) {
+void InitialInstance::UnserializeFrom(gd::Project &project,
+                                      const SerializerElement &element) {
   SetObjectName(element.GetStringAttribute("name", "", "nom"));
   SetX(element.GetDoubleAttribute("x"));
   SetY(element.GetDoubleAttribute("y"));
@@ -131,6 +118,11 @@ void InitialInstance::UnserializeFrom(const SerializerElement& element) {
     GetVariables().UnserializeFrom(
         element.GetChild("initialVariables", 0, "InitialVariables"));
   }
+
+  if (element.HasChild("behaviorOverridings")) {
+    behaviorOverridings.UnserializeFrom(
+        project, element.GetChild("behaviorOverridings"));
+  }
 }
 
 void InitialInstance::SerializeTo(SerializerElement& element) const {
@@ -178,6 +170,10 @@ void InitialInstance::SerializeTo(SerializerElement& element) const {
   }
 
   GetVariables().SerializeTo(element.AddChild("initialVariables"));
+
+  if (!behaviorOverridings.GetAllBehaviorContents().empty()) {
+    behaviorOverridings.SerializeTo(element.AddChild("behaviorOverridings"));
+  }
 }
 
 InitialInstance& InitialInstance::ResetPersistentUuid() {
@@ -243,4 +239,70 @@ void InitialInstance::SetRawStringProperty(const gd::String& name,
   stringProperties[name] = value;
 }
 
+bool InitialInstance::HasAnyOverriddenProperty(const gd::Object &object) {
+  for (auto &behaviorOverridingPair : behaviorOverridings.GetAllBehaviorContents()) {
+    auto &behaviorName = behaviorOverridingPair.first;
+    if (HasAnyOverriddenPropertyForBehavior(object.GetBehavior(behaviorName))) {
+      return true;
+    }
+  }
+  return false;
+}
+
+bool InitialInstance::HasAnyOverriddenPropertyForBehavior(
+    const gd::Behavior &behavior) {
+  auto &behaviorName = behavior.GetName();
+  if (!HasBehaviorOverridingNamed(behaviorName)) {
+    return false;
+  }
+  auto &behaviorOverriding = GetBehaviorOverriding(behaviorName);
+  if (behaviorOverriding.GetContent().IsEmpty()) {
+    return false;
+  }
+  const auto &overridingProperties = behaviorOverriding.GetProperties();
+  for (auto &propertyPair : behavior.GetProperties()) {
+    auto &propertyName = propertyPair.first;
+    auto &behaviorProperty = propertyPair.second;
+
+    if (behaviorProperty.GetType() != "Behavior" &&
+        behaviorOverriding.HasPropertyValue(propertyName) &&
+        overridingProperties.find(propertyName) !=
+            overridingProperties.end() &&
+        overridingProperties.at(propertyName).GetValue() !=
+            behaviorProperty.GetValue()) {
+      return true;
+    }
+  }
+  return false;
+}
+
+gd::Behavior &InitialInstance::GetBehaviorOverriding(const gd::String &name) {
+  return behaviorOverridings.GetBehavior(name);
+}
+
+const gd::Behavior &
+InitialInstance::GetBehaviorOverriding(const gd::String &name) const {
+  return behaviorOverridings.GetBehavior(name);
+}
+
+bool InitialInstance::HasBehaviorOverridingNamed(const gd::String &name) const {
+  return behaviorOverridings.HasBehaviorNamed(name);
+}
+
+void InitialInstance::RemoveBehaviorOverriding(const gd::String &name) {
+  behaviorOverridings.RemoveBehavior(name);
+}
+
+bool InitialInstance::RenameBehaviorOverriding(const gd::String &name,
+                                               const gd::String &newName) {
+  return behaviorOverridings.RenameBehavior(name, newName);
+}
+
+gd::Behavior *
+InitialInstance::AddNewBehaviorOverriding(const gd::Project &project,
+                                          const gd::String &type,
+                                          const gd::String &name) {
+  return behaviorOverridings.AddNewBehavior(project, type, name);
+}
+
 }  // namespace gd
diff --git a/Core/GDCore/Project/InitialInstance.h b/Core/GDCore/Project/InitialInstance.h
index 831feb063..a84983da8 100644
--- a/Core/GDCore/Project/InitialInstance.h
+++ b/Core/GDCore/Project/InitialInstance.h
@@ -9,12 +9,15 @@
 #include <map>
 
 #include "GDCore/Project/VariablesContainer.h"
+#include "GDCore/Project/BehaviorsContainer.h"
 #include "GDCore/String.h"
 namespace gd {
 class PropertyDescriptor;
 class Project;
 class Layout;
 class ObjectsContainer;
+class Object;
+class Behavior;
 }  // namespace gd
 
 namespace gd {
@@ -286,6 +289,67 @@ class GD_CORE_API InitialInstance {
   gd::VariablesContainer& GetVariables() { return initialVariables; }
   ///@}
 
+  /** \name Behavior management
+   * Members functions related to behavior overridings management.
+   */
+  ///@{
+
+  /**
+   * \brief Return `true` if any property from the overriding has a different
+   * value from any behavior.
+   */
+  bool HasAnyOverriddenProperty(const gd::Object &object);
+
+  /**
+   * \brief Return `true` if any property from the overriding has a different
+   * value from the given behavior.
+   */
+  bool HasAnyOverriddenPropertyForBehavior(const gd::Behavior &behavior);
+
+  /**
+   * \brief Return a reference to the content of the overriding of of the
+   * behavior called \a name.
+   */
+  Behavior &GetBehaviorOverriding(const gd::String &name);
+
+  /**
+   * \brief Return a reference to the content of the overriding of the behavior
+   * called \a name.
+   */
+  const Behavior &GetBehaviorOverriding(const gd::String &name) const;
+
+  /**
+   * \brief Return true if the object instance overrides the object behavior
+   * called \a name.
+   */
+  bool HasBehaviorOverridingNamed(const gd::String &name) const;
+
+  /**
+   * \brief Remove the behavior overrides for the behavior called \a name
+   */
+  void RemoveBehaviorOverriding(const gd::String &name);
+
+  /**
+   * \brief Change the name of behavior called name to newName.
+   * \return true if name was successfully changed
+   */
+  bool RenameBehaviorOverriding(const gd::String &name,
+                                const gd::String &newName);
+
+  /**
+   * \brief Add the behavior of the specified \a type with the specified \a
+   * name.
+   *
+   * The project's current platform is used to initialize the content.
+   *
+   * \return A pointer to the newly added behavior content. NULL if the creation
+   * failed.
+   */
+  gd::Behavior *AddNewBehaviorOverriding(const gd::Project &project,
+                                         const gd::String &type,
+                                         const gd::String &name);
+  ///@}
+
   /** \name Others properties management
    * Members functions related to exposing others properties of the instance.
    *
@@ -365,7 +429,8 @@ class GD_CORE_API InitialInstance {
   /**
    * \brief Unserialize the instances container.
    */
-  virtual void UnserializeFrom(const SerializerElement& element);
+  virtual void UnserializeFrom(gd::Project &project,
+                               const SerializerElement &element);
 
   /**
    * \brief Reset the persistent UUID used to recognize
@@ -376,8 +441,8 @@ class GD_CORE_API InitialInstance {
   /**
    * \brief Reset the persistent UUID used to recognize
    * the same initial instance between serialization.
-   */
-  const gd::String& GetPersistentUuid() const { return persistentUuid; }
+   */
+  const gd::String& GetPersistentUuid() const { return persistentUuid; }
   ///@}
 
  private:
@@ -388,32 +453,36 @@ class GD_CORE_API InitialInstance {
   std::map<gd::String, gd::String>
       stringProperties;  ///< More data which can be used by the object
 
-  gd::String objectName;  ///< Object name
-  double x;               ///< Instance X position
-  double y;               ///< Instance Y position
-  double z;               ///< Instance Z position (for a 3D object)
-  double angle;           ///< Instance angle on Z axis
-  double rotationX;       ///< Instance angle on X axis (for a 3D object)
-  double rotationY;       ///< Instance angle on Y axis (for a 3D object)
-  int zOrder;             ///< Instance Z order (for a 2D object)
-  int opacity;            ///< Instance opacity
-  bool flippedX;          ///< True if the instance is flipped on X axis
-  bool flippedY;          ///< True if the instance is flipped on Y axis
-  bool flippedZ;          ///< True if the instance is flipped on Z axis
-  gd::String layer;       ///< Instance layer
-  bool customSize;        ///< True if object has a custom width and height
-  bool customDepth;       ///< True if object has a custom depth
-  double width;           ///< Instance custom width
-  double height;          ///< Instance custom height
-  double depth;           ///< Instance custom depth
+  gd::String objectName;    ///< Object name
+  double x = 0;             ///< Instance X position
+  double y = 0;             ///< Instance Y position
+  double z = 0;             ///< Instance Z position (for a 3D object)
+  double angle = 0;         ///< Instance angle on Z axis
+  double rotationX = 0;     ///< Instance angle on X axis (for a 3D object)
+  double rotationY = 0;     ///< Instance angle on Y axis (for a 3D object)
+  int zOrder = 0;           ///< Instance Z order (for a 2D object)
+  int opacity = 255;        ///< Instance opacity
+  bool flippedX = false;    ///< True if the instance is flipped on X axis
+  bool flippedY = false;    ///< True if the instance is flipped on Y axis
+  bool flippedZ = false;    ///< True if the instance is flipped on Z axis
+  gd::String layer;         ///< Instance layer
+  bool customSize = false;  ///< True if object has a custom width and height
+  bool customDepth = false; ///< True if object has a custom depth
+  double width = 0;         ///< Instance custom width
+  double height = 0;        ///< Instance custom height
+  double depth = 0;         ///< Instance custom depth
   double defaultWidth = 0;  ///< Instance default width as reported by InGameEditor
   double defaultHeight = 0; ///< Instance default height as reported by InGameEditor
   double defaultDepth = 0;  ///< Instance default depth as reported by InGameEditor
   gd::VariablesContainer initialVariables;  ///< Instance specific variables
-  bool locked;                              ///< True if the instance is locked
-  bool sealed;                              ///< True if the instance is sealed
-  bool keepRatio;                     ///< True if the instance's dimensions
-                                      ///  should keep the same ratio.
+  gd::BehaviorsContainer
+      behaviorOverridings; ///< Contains all behavior property overriding for
+                           ///< the instance. Behavior contents are the
+                           ///< ownership of the instance.
+  bool locked = false;     ///< True if the instance is locked
+  bool sealed = false;     ///< True if the instance is sealed
+  bool keepRatio = true;   ///< True if the instance's dimensions
+                           ///  should keep the same ratio.
   mutable gd::String persistentUuid;  ///< A persistent random version 4 UUID,
                                       ///  useful for hot reloading.
 
diff --git a/Core/GDCore/Project/InitialInstancesContainer.cpp b/Core/GDCore/Project/InitialInstancesContainer.cpp
index e7cc5b0ed..e9c838a8b 100644
--- a/Core/GDCore/Project/InitialInstancesContainer.cpp
+++ b/Core/GDCore/Project/InitialInstancesContainer.cpp
@@ -25,13 +25,13 @@ std::size_t InitialInstancesContainer::GetInstancesCount() const {
 }
 
 void InitialInstancesContainer::UnserializeFrom(
-    const SerializerElement& element) {
+    gd::Project &project, const SerializerElement &element) {
   initialInstances.clear();
 
   element.ConsiderAsArrayOf("instance", "Objet");
   for (std::size_t i = 0; i < element.GetChildrenCount(); ++i) {
     gd::InitialInstance instance;
-    instance.UnserializeFrom(element.GetChild(i));
+    instance.UnserializeFrom(project, element.GetChild(i));
     initialInstances.push_back(instance);
   }
 }
diff --git a/Core/GDCore/Project/InitialInstancesContainer.h b/Core/GDCore/Project/InitialInstancesContainer.h
index 2bb3c3a4c..163ed512a 100644
--- a/Core/GDCore/Project/InitialInstancesContainer.h
+++ b/Core/GDCore/Project/InitialInstancesContainer.h
@@ -187,10 +187,11 @@ class GD_CORE_API InitialInstancesContainer {
   /**
    * \brief Unserialize the instances container.
    */
-  virtual void UnserializeFrom(const SerializerElement &element);
+  virtual void UnserializeFrom(gd::Project &project,
+                               const SerializerElement &element);
   ///@}
 
- private:
+private:
   void RemoveInstanceIf(
       std::function<bool(const gd::InitialInstance &)> predicate);
 
diff --git a/Core/GDCore/Project/Layout.cpp b/Core/GDCore/Project/Layout.cpp
index 42bbd1da9..d631e411f 100644
--- a/Core/GDCore/Project/Layout.cpp
+++ b/Core/GDCore/Project/Layout.cpp
@@ -334,7 +334,7 @@ void Layout::UnserializeFrom(gd::Project& project,
   objectsContainer.AddMissingObjectsInRootFolder();
 
   initialInstances.UnserializeFrom(
-      element.GetChild("instances", 0, "Positions"));
+      project, element.GetChild("instances", 0, "Positions"));
   variables.UnserializeFrom(element.GetChild("variables", 0, "Variables"));
 
   layers.UnserializeLayersFrom(element.GetChild("layers", 0, "Layers"));
diff --git a/Core/GDCore/Project/Object.cpp b/Core/GDCore/Project/Object.cpp
index a2d660f9f..493b617b2 100644
--- a/Core/GDCore/Project/Object.cpp
+++ b/Core/GDCore/Project/Object.cpp
@@ -51,7 +51,7 @@ void Object::CopyWithoutConfiguration(const gd::Object& object) {
   assetStoreId = object.assetStoreId;
   objectVariables = object.objectVariables;
   effectsContainer = object.effectsContainer;
-  behaviors = gd::Clone(object.behaviors);
+  behaviors = object.behaviors;
 }
 
 gd::ObjectConfiguration& Object::GetConfiguration() { return *configuration; }
@@ -61,69 +61,31 @@ const gd::ObjectConfiguration& Object::GetConfiguration() const {
 }
 
 std::vector<gd::String> Object::GetAllBehaviorNames() const {
-  std::vector<gd::String> allNameIdentifiers;
-
-  for (auto& it : behaviors) allNameIdentifiers.push_back(it.first);
-
-  return allNameIdentifiers;
+  return behaviors.GetAllBehaviorNames();
 }
 
-void Object::RemoveBehavior(const gd::String& name) { behaviors.erase(name); }
+void Object::RemoveBehavior(const gd::String& name) { behaviors.RemoveBehavior(name); }
 
 bool Object::RenameBehavior(const gd::String& name, const gd::String& newName) {
-  if (behaviors.find(name) == behaviors.end() ||
-      behaviors.find(newName) != behaviors.end())
-    return false;
-
-  std::unique_ptr<Behavior> aut = std::move(behaviors.find(name)->second);
-  behaviors.erase(name);
-  behaviors[newName] = std::move(aut);
-  behaviors[newName]->SetName(newName);
-
-  return true;
+  return behaviors.RenameBehavior(name, newName);
 }
 
 gd::Behavior& Object::GetBehavior(const gd::String& name) {
-  return *behaviors.find(name)->second;
+  return behaviors.GetBehavior(name);
 }
 
 const gd::Behavior& Object::GetBehavior(const gd::String& name) const {
-  return *behaviors.find(name)->second;
+  return behaviors.GetBehavior(name);
 }
 
 bool Object::HasBehaviorNamed(const gd::String& name) const {
-  return behaviors.find(name) != behaviors.end();
+  return behaviors.HasBehaviorNamed(name);
 }
 
 gd::Behavior* Object::AddNewBehavior(const gd::Project& project,
                                      const gd::String& type,
                                      const gd::String& name) {
-  auto initializeAndAdd = [this,
-                           &name](std::unique_ptr<gd::Behavior> behavior) {
-    behavior->InitializeContent();
-    this->behaviors[name] = std::move(behavior);
-    return this->behaviors[name].get();
-  };
-
-  if (project.HasEventsBasedBehavior(type)) {
-    return initializeAndAdd(
-        gd::make_unique<CustomBehavior>(name, project, type));
-  } else {
-    const gd::BehaviorMetadata& behaviorMetadata =
-        gd::MetadataProvider::GetBehaviorMetadata(project.GetCurrentPlatform(),
-                                                  type);
-    if (gd::MetadataProvider::IsBadBehaviorMetadata(behaviorMetadata)) {
-      gd::LogWarning("Tried to create a behavior with an unknown type: " +
-                     type + " on object " + GetName() + "!");
-      // It's probably an events-based behavior that was removed.
-      // Create a custom behavior to preserve the properties values.
-      return initializeAndAdd(
-          gd::make_unique<CustomBehavior>(name, project, type));
-    }
-    std::unique_ptr<gd::Behavior> behavior(behaviorMetadata.Get().Clone());
-    behavior->SetName(name);
-    return initializeAndAdd(std::move(behavior));
-  }
+  return behaviors.AddNewBehavior(project, type, name);
 }
 
 void Object::UnserializeFrom(gd::Project& project,
@@ -145,7 +107,7 @@ void Object::UnserializeFrom(gd::Project& project,
   // Compatibility with GD <= 3.3
   if (element.HasChild("Automatism")) {
     for (std::size_t i = 0; i < element.GetChildrenCount("Automatism"); ++i) {
-      SerializerElement& behaviorElement = element.GetChild("Automatism", i);
+      SerializerElement &behaviorElement = element.GetChild("Automatism", i);
 
       gd::String type = behaviorElement.GetStringAttribute("type", "", "Type")
                             .FindAndReplace("Automatism", "Behavior");
@@ -157,59 +119,9 @@ void Object::UnserializeFrom(gd::Project& project,
   }
   // End of compatibility code
   else {
-    SerializerElement& behaviorsElement =
+    SerializerElement &behaviorsElement =
         element.GetChild("behaviors", 0, "automatisms");
-    behaviorsElement.ConsiderAsArrayOf("behavior", "automatism");
-    for (std::size_t i = 0; i < behaviorsElement.GetChildrenCount(); ++i) {
-      SerializerElement& behaviorElement = behaviorsElement.GetChild(i);
-
-      gd::String type =
-          behaviorElement.GetStringAttribute("type").FindAndReplace(
-              "Automatism", "Behavior");  // Compatibility with GD <= 4
-      gd::String name = behaviorElement.GetStringAttribute("name");
-
-      auto behavior = gd::Object::AddNewBehavior(project, type, name);
-      // Compatibility with GD <= 4.0.98
-      // If there is only one child called "content" (in addition to "type" and
-      // "name"), it's the content of a JavaScript behavior. Move the content
-      // out of the "content" object (to put it directly at the root of the
-      // behavior element).
-      if (behaviorElement.HasChild("content") &&
-          behaviorElement.GetAllChildren().size() == 3) {
-        SerializerElement& contentElement = behaviorElement.GetChild("content");
-
-        // Physics2 Behavior was using "type" for the type of the body. The name
-        // conflicts with the behavior "type". Rename it.
-        if (contentElement.HasChild("type")) {
-          contentElement.AddChild("bodyType")
-              .SetValue(contentElement.GetChild("type").GetStringValue());
-          contentElement.RemoveChild("type");
-        }
-
-        behavior->UnserializeFrom(contentElement);
-      }
-      // end of compatibility code
-      else {
-        behavior->UnserializeFrom(behaviorElement);
-      }
-
-      bool isFolded = behaviorElement.GetBoolAttribute("isFolded", false);
-      behavior->SetFolded(isFolded);
-
-      // Handle Quick Customization info.
-      if (behaviorElement.HasChild(
-              "propertiesQuickCustomizationVisibilities")) {
-        behavior->GetPropertiesQuickCustomizationVisibilities().UnserializeFrom(
-            behaviorElement.GetChild(
-                "propertiesQuickCustomizationVisibilities"));
-      }
-      if (behaviorElement.HasChild("quickCustomizationVisibility")) {
-        behavior->SetQuickCustomizationVisibility(
-            QuickCustomization::StringAsVisibility(
-                behaviorElement.GetStringAttribute(
-                    "quickCustomizationVisibility")));
-      }
-    }
+    behaviors.UnserializeFrom(project, behaviorsElement);
   }
 
   configuration->UnserializeFrom(project, element);
@@ -224,48 +136,7 @@ void Object::SerializeTo(SerializerElement& element) const {
   element.SetAttribute("type", GetType());
   objectVariables.SerializeTo(element.AddChild("variables"));
   effectsContainer.SerializeTo(element.AddChild("effects"));
-
-  SerializerElement& behaviorsElement = element.AddChild("behaviors");
-  behaviorsElement.ConsiderAsArrayOf("behavior");
-  std::vector<gd::String> allBehaviors = GetAllBehaviorNames();
-  for (std::size_t i = 0; i < allBehaviors.size(); ++i) {
-    const gd::Behavior& behavior = GetBehavior(allBehaviors[i]);
-    // Default behaviors are added at the object creation according to
-    // metadata. They don't need to be serialized.
-    // During the export, all behaviors are set as not default by
-    // `BehaviorDefaultFlagClearer` because the Runtime needs all the behaviors.
-    if (behavior.IsDefaultBehavior()) {
-      continue;
-    }
-    SerializerElement& behaviorElement = behaviorsElement.AddChild("behavior");
-
-    behavior.SerializeTo(behaviorElement);
-    behaviorElement.RemoveChild("type");  // The content can contain type or
-                                          // name properties, remove them.
-    behaviorElement.RemoveChild("name");
-    behaviorElement.RemoveChild("isFolded");
-    behaviorElement.SetAttribute("type", behavior.GetTypeName());
-    behaviorElement.SetAttribute("name", behavior.GetName());
-    if (behavior.IsFolded()) behaviorElement.SetAttribute("isFolded", true);
-
-    // Handle Quick Customization info.
-    behaviorElement.RemoveChild("propertiesQuickCustomizationVisibilities");
-    const QuickCustomizationVisibilitiesContainer&
-        propertiesQuickCustomizationVisibilities =
-            behavior.GetPropertiesQuickCustomizationVisibilities();
-    if (!propertiesQuickCustomizationVisibilities.IsEmpty()) {
-      propertiesQuickCustomizationVisibilities.SerializeTo(
-          behaviorElement.AddChild("propertiesQuickCustomizationVisibilities"));
-    }
-    const QuickCustomization::Visibility visibility =
-        behavior.GetQuickCustomizationVisibility();
-    if (visibility != QuickCustomization::Visibility::Default) {
-      behaviorElement.SetAttribute(
-          "quickCustomizationVisibility",
-          QuickCustomization::VisibilityAsString(visibility));
-    }
-  }
-
+  behaviors.SerializeTo(element.AddChild("behaviors"));
   configuration->SerializeTo(element);
 }
 
diff --git a/Core/GDCore/Project/Object.h b/Core/GDCore/Project/Object.h
index a9eaeb354..61ecca6f8 100644
--- a/Core/GDCore/Project/Object.h
+++ b/Core/GDCore/Project/Object.h
@@ -10,6 +10,7 @@
 #include <vector>
 
 #include "GDCore/Project/Behavior.h"
+#include "GDCore/Project/BehaviorsContainer.h"
 #include "GDCore/Project/EffectsContainer.h"
 #include "GDCore/Project/ObjectConfiguration.h"
 #include "GDCore/Project/VariablesContainer.h"
@@ -180,7 +181,7 @@ class GD_CORE_API Object {
    */
   const std::map<gd::String, std::unique_ptr<gd::Behavior>>&
   GetAllBehaviorContents() const {
-    return behaviors;
+    return behaviors.GetAllBehaviorContents();
   };
   ///@}
 
@@ -253,10 +254,10 @@ class GD_CORE_API Object {
   gd::String assetStoreId;  ///< The ID of the asset if the object comes from
                             ///< the store.
   std::unique_ptr<gd::ObjectConfiguration> configuration;
-  std::map<gd::String, std::unique_ptr<gd::Behavior>>
-      behaviors;  ///< Contains all behaviors and their properties for the
-                  ///< object. Behavior contents are the ownership of the
-                  ///< object.
+  gd::BehaviorsContainer
+      behaviors; ///< Contains all behaviors and their properties for the
+                 ///< object. Behavior contents are the ownership of the
+                 ///< object.
   gd::VariablesContainer
       objectVariables;  ///< List of the variables of the object
   gd::EffectsContainer
diff --git a/Core/GDCore/Project/Project.cpp b/Core/GDCore/Project/Project.cpp
index 38aec183a..d96b48f74 100644
--- a/Core/GDCore/Project/Project.cpp
+++ b/Core/GDCore/Project/Project.cpp
@@ -915,7 +915,7 @@ void Project::UnserializeFrom(const SerializerElement& element) {
 
     gd::ExternalLayout& newExternalLayout =
         InsertNewExternalLayout("", GetExternalLayoutsCount());
-    newExternalLayout.UnserializeFrom(externalLayoutElement);
+    newExternalLayout.UnserializeFrom(*this, externalLayoutElement);
   }
 }
 
diff --git a/Core/GDCore/Serialization/SerializerElement.cpp b/Core/GDCore/Serialization/SerializerElement.cpp
index bde56aeed..0478c9622 100644
--- a/Core/GDCore/Serialization/SerializerElement.cpp
+++ b/Core/GDCore/Serialization/SerializerElement.cpp
@@ -283,6 +283,19 @@ void SerializerElement::RemoveChild(const gd::String& name) {
   }
 }
 
+void SerializerElement::Clear() {
+  children.clear();
+  attributes.clear();
+}
+
+bool SerializerElement::IsEmpty() {
+  return children.empty() && attributes.empty();
+}
+
+void SerializerElement::RemoveAttribute(const gd::String& name) {
+  attributes.erase(name);
+}
+
 void SerializerElement::Init(const gd::SerializerElement& other) {
   valueUndefined = other.valueUndefined;
   elementValue = other.elementValue;
diff --git a/Core/GDCore/Serialization/SerializerElement.h b/Core/GDCore/Serialization/SerializerElement.h
index 40614eed2..d0a4adf17 100644
--- a/Core/GDCore/Serialization/SerializerElement.h
+++ b/Core/GDCore/Serialization/SerializerElement.h
@@ -329,6 +329,12 @@ class GD_CORE_API SerializerElement {
    */
   bool HasAttribute(const gd::String &name) const;
 
+  /**
+   * \brief Remove the attribute with the specified name
+   * \param name The name of the attribute to remove.
+   */
+  void RemoveAttribute(const gd::String& name);
+
   /**
    * \brief Return all the attributes of the element.
    */
@@ -438,6 +444,13 @@ class GD_CORE_API SerializerElement {
    */
   void RemoveChild(const gd::String &name);
 
+  /**
+   * \brief Remove all children and attributes.
+   */
+  void Clear();
+
+  bool IsEmpty();
+
   /**
    * \brief Return all the children of the element.
    */
diff --git a/Core/tests/DummyPlatform.cpp b/Core/tests/DummyPlatform.cpp
index b409b9732..9e888804d 100644
--- a/Core/tests/DummyPlatform.cpp
+++ b/Core/tests/DummyPlatform.cpp
@@ -20,6 +20,62 @@
 #include "GDCore/Extensions/Metadata/ParameterOptions.h"
 #include "catch.hpp"
 
+class BehaviorWithProperties : public gd::Behavior {
+ public:
+  BehaviorWithProperties(
+      const gd::String& name, const gd::String& type)
+      : Behavior(name, type) {};
+  virtual ~BehaviorWithProperties(){};
+  virtual std::unique_ptr<gd::Behavior> Clone() const override {
+    return gd::make_unique<BehaviorWithProperties>(*this);
+  }
+
+  virtual std::map<gd::String, gd::PropertyDescriptor> GetProperties(
+      const gd::SerializerElement& behaviorContent) const override {
+    std::map<gd::String, gd::PropertyDescriptor> properties;
+    properties["numberProperty"]
+        .SetLabel("Number property")
+        .SetValue(
+            gd::String::From(behaviorContent.GetChild("numberProperty").GetDoubleValue()))
+        .SetType("Number");
+    properties["stringProperty"]
+        .SetLabel("String property")
+        .SetValue(
+            behaviorContent.GetChild("stringProperty").GetStringValue())
+        .SetType("String");
+    properties["booleanProperty"]
+        .SetLabel("Boolean property")
+        .SetValue(
+            behaviorContent.GetChild("booleanProperty").GetBoolValue() ? "true" : "false")
+        .SetType("Boolean");
+    return properties;
+  }
+  virtual bool UpdateProperty(gd::SerializerElement& behaviorContent,
+                              const gd::String& name,
+                              const gd::String& value) override {
+    auto &element = behaviorContent.AddChild(name);
+    if (name == "numberProperty") {
+      element.SetDoubleValue(value.To<double>());
+      return true;
+    }
+    if (name == "stringProperty") {
+      element.SetStringValue(value);
+      return true;
+    }
+    if (name == "booleanProperty") {
+      element.SetBoolValue(value == "1");
+      return true;
+    }
+    return false;
+  }
+  virtual void InitializeContent(
+      gd::SerializerElement& behaviorContent) override {
+   behaviorContent.AddChild("numberProperty").SetDoubleValue(123);
+   behaviorContent.AddChild("stringProperty").SetStringValue("ABC");
+   behaviorContent.AddChild("booleanProperty").SetBoolValue(true);
+  }
+};
+
 // TODO Remove these 2 classes and write the test with events based behaviors.
 class BehaviorWithRequiredBehaviorProperty : public gd::Behavior {
  public:
@@ -564,7 +620,7 @@ void SetupProjectWithDummyPlatform(gd::Project& project,
                                "Group",
                                "Icon.png",
                                "MyBehavior",
-                               gd::make_unique<gd::Behavior>(
+                               gd::make_unique<BehaviorWithProperties>(
                                   "Behavior", "MyExtension::MyBehavior"),
                                gd::make_unique<gd::BehaviorsSharedData>());
     behavior
diff --git a/Core/tests/InitialInstance.cpp b/Core/tests/InitialInstance.cpp
index 588f02ab6..a49966bf9 100644
--- a/Core/tests/InitialInstance.cpp
+++ b/Core/tests/InitialInstance.cpp
@@ -12,18 +12,109 @@
 #include <initializer_list>
 #include <map>
 
+#include "DummyPlatform.h"
 #include "GDCore/CommonTools.h"
+#include "GDCore/Extensions/Platform.h"
 #include "GDCore/Project/InitialInstance.h"
+#include "GDCore/Project/Layout.h"
+#include "GDCore/Project/Object.h"
+#include "GDCore/Project/Project.h"
+#include "GDCore/Project/PropertyDescriptor.h"
 #include "GDCore/Tools/VersionWrapper.h"
 
 TEST_CASE("InitialInstance", "[common][instances]") {
-  gd::InitialInstance instance;
 
   SECTION("GetRawDoubleProperty") {
+    gd::InitialInstance instance;
     REQUIRE(instance.GetRawDoubleProperty("NotExistingProperty") == 0);
   }
 
   SECTION("GetRawStringProperty") {
+    gd::InitialInstance instance;
     REQUIRE(instance.GetRawStringProperty("NotExistingProperty") == "");
   }
+
+  SECTION("Can create an instance without behavior property overriding") {
+    gd::Platform platform;
+    gd::Project project;
+    SetupProjectWithDummyPlatform(project, platform);
+
+    gd::Layout &layout = project.InsertNewLayout("Scene", 0);
+    gd::Object &object = layout.GetObjects().InsertNewObject(
+        project, "MyExtension::FakeObjectWithDefaultBehavior", "MyObject", 0);
+    object.AddNewBehavior(project, "MyExtension::MyBehavior", "MyBehavior");
+    REQUIRE(object.HasBehaviorNamed("MyBehavior") == true);
+    gd::Behavior &behavior = object.GetBehavior("MyBehavior");
+
+    gd::InitialInstance instance;
+    instance.SetObjectName("MyObject");
+    REQUIRE(instance.HasAnyOverriddenProperty(object) == false);
+    REQUIRE(instance.HasAnyOverriddenPropertyForBehavior(behavior) == false);
+    REQUIRE(instance.HasBehaviorOverridingNamed("MyBehavior") == false);
+  }
+
+  SECTION("Can add and remove behavior property overridings on an instance") {
+    gd::Platform platform;
+    gd::Project project;
+    SetupProjectWithDummyPlatform(project, platform);
+
+    gd::Layout &layout = project.InsertNewLayout("Scene", 0);
+    gd::Object &object = layout.GetObjects().InsertNewObject(
+        project, "MyExtension::FakeObjectWithDefaultBehavior", "MyObject", 0);
+    object.AddNewBehavior(project, "MyExtension::MyBehavior", "MyBehavior");
+    REQUIRE(object.HasBehaviorNamed("MyBehavior") == true);
+    gd::Behavior &behavior = object.GetBehavior("MyBehavior");
+
+    gd::InitialInstance instance;
+    instance.SetObjectName("MyObject");
+    instance.AddNewBehaviorOverriding(project, "MyExtension::MyBehavior",
+                                      "MyBehavior");
+    REQUIRE(instance.HasBehaviorOverridingNamed("MyBehavior") == true);
+    gd::Behavior &behaviorOverriding =
+        instance.GetBehaviorOverriding("MyBehavior");
+
+    // The behavior overriding is empty by default.
+    REQUIRE(instance.HasAnyOverriddenProperty(object) == false);
+    REQUIRE(instance.HasAnyOverriddenPropertyForBehavior(behavior) == false);
+    REQUIRE(behaviorOverriding.HasPropertyValue("numberProperty") == false);
+    REQUIRE(behaviorOverriding.HasPropertyValue("stringProperty") == false);
+    REQUIRE(behaviorOverriding.HasPropertyValue("booleanProperty") == false);
+
+    // Add some behavior property overridings
+    behaviorOverriding.UpdateProperty("numberProperty", "456");
+    REQUIRE(
+        behaviorOverriding.GetProperties().at("numberProperty").GetValue() ==
+        "456");
+    REQUIRE(behaviorOverriding.HasPropertyValue("numberProperty") == true);
+    REQUIRE(instance.HasAnyOverriddenProperty(object) == true);
+    REQUIRE(instance.HasAnyOverriddenPropertyForBehavior(behavior) == true);
+
+    behaviorOverriding.UpdateProperty("stringProperty", "DEF");
+    REQUIRE(
+        behaviorOverriding.GetProperties().at("stringProperty").GetValue() ==
+        "DEF");
+    REQUIRE(behaviorOverriding.HasPropertyValue("stringProperty") == true);
+
+    behaviorOverriding.UpdateProperty("booleanProperty", "false");
+    REQUIRE(behaviorOverriding.HasPropertyValue("booleanProperty") == true);
+    REQUIRE(
+        behaviorOverriding.GetProperties().at("booleanProperty").GetValue() ==
+        "false");
+
+    // The user set back original values from the object behavior.
+    // The IDE removes the behavior property overridings accordingly.
+    behaviorOverriding.RemoveProperty("numberProperty");
+    REQUIRE(behaviorOverriding.HasPropertyValue("numberProperty") == false);
+    behaviorOverriding.RemoveProperty("stringProperty");
+    REQUIRE(behaviorOverriding.HasPropertyValue("stringProperty") == false);
+    behaviorOverriding.RemoveProperty("booleanProperty");
+    REQUIRE(behaviorOverriding.HasPropertyValue("booleanProperty") == false);
+
+    // No more property is overriden
+    REQUIRE(instance.HasAnyOverriddenPropertyForBehavior(behavior) == false);
+    REQUIRE(instance.HasAnyOverriddenProperty(object) == false);
+
+    // The IDE removes the behavior overriding accordingly.
+    instance.RemoveBehaviorOverriding("MyBehavior");
+  }
 }
diff --git a/Extensions/3D/A_RuntimeObject3D.ts b/Extensions/3D/A_RuntimeObject3D.ts
index 652580947..d2adee49d 100644
--- a/Extensions/3D/A_RuntimeObject3D.ts
+++ b/Extensions/3D/A_RuntimeObject3D.ts
@@ -70,9 +70,10 @@ namespace gdjs {
 
     constructor(
       instanceContainer: gdjs.RuntimeInstanceContainer,
-      objectData: gdjs.Object3DData
+      objectData: gdjs.Object3DData,
+      instanceData: InstanceData | undefined
     ) {
-      super(instanceContainer, objectData);
+      super(instanceContainer, objectData, instanceData);
       // TODO Should 0 be replaced by 0.01 instead of using the default value?
       this._width = this._originalWidth = getValidDimensionValue(
         objectData.content.width
diff --git a/Extensions/3D/Base3DBehavior.ts b/Extensions/3D/Base3DBehavior.ts
index 860da413c..a0e5e6b2a 100644
--- a/Extensions/3D/Base3DBehavior.ts
+++ b/Extensions/3D/Base3DBehavior.ts
@@ -174,7 +174,7 @@ namespace gdjs {
       this.object = owner;
     }
 
-    updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
+    override applyBehaviorOverriding(behaviorData): boolean {
       // Nothing to update.
       return true;
     }
diff --git a/Extensions/3D/Cube3DRuntimeObject.ts b/Extensions/3D/Cube3DRuntimeObject.ts
index 1ffd1cffb..762405645 100644
--- a/Extensions/3D/Cube3DRuntimeObject.ts
+++ b/Extensions/3D/Cube3DRuntimeObject.ts
@@ -84,9 +84,10 @@ namespace gdjs {
 
     constructor(
       instanceContainer: gdjs.RuntimeInstanceContainer,
-      objectData: Cube3DObjectData
+      objectData: Cube3DObjectData,
+      instanceData?: InstanceData
     ) {
-      super(instanceContainer, objectData);
+      super(instanceContainer, objectData, instanceData);
       this._shouldUseTransparentTexture =
         objectData.content.enableTextureTransparency || false;
       this._facesOrientation = objectData.content.facesOrientation || 'Y';
diff --git a/Extensions/3D/CustomRuntimeObject3D.ts b/Extensions/3D/CustomRuntimeObject3D.ts
index ca6f94210..32e4db6f1 100644
--- a/Extensions/3D/CustomRuntimeObject3D.ts
+++ b/Extensions/3D/CustomRuntimeObject3D.ts
@@ -44,9 +44,10 @@ namespace gdjs {
 
     constructor(
       parent: gdjs.RuntimeInstanceContainer,
-      objectData: gdjs.Object3DData & gdjs.CustomObjectConfiguration
+      objectData: gdjs.Object3DData & gdjs.CustomObjectConfiguration,
+      instanceData?: InstanceData
     ) {
-      super(parent, objectData);
+      super(parent, objectData, instanceData);
     }
 
     protected override _createRender() {
diff --git a/Extensions/3D/Model3DRuntimeObject.ts b/Extensions/3D/Model3DRuntimeObject.ts
index 483f96473..5c6aba48f 100644
--- a/Extensions/3D/Model3DRuntimeObject.ts
+++ b/Extensions/3D/Model3DRuntimeObject.ts
@@ -114,9 +114,10 @@ namespace gdjs {
 
     constructor(
       instanceContainer: gdjs.RuntimeInstanceContainer,
-      objectData: Model3DObjectData
+      objectData: Model3DObjectData,
+      instanceData?: InstanceData
     ) {
-      super(instanceContainer, objectData);
+      super(instanceContainer, objectData, instanceData);
       this._data = objectData;
       this._modelResourceName = objectData.content.modelResourceName;
       this._animations = objectData.content.animations;
diff --git a/Extensions/AnchorBehavior/anchorruntimebehavior.ts b/Extensions/AnchorBehavior/anchorruntimebehavior.ts
index 33dc202e6..c06844b58 100644
--- a/Extensions/AnchorBehavior/anchorruntimebehavior.ts
+++ b/Extensions/AnchorBehavior/anchorruntimebehavior.ts
@@ -68,32 +68,24 @@ namespace gdjs {
           : behaviorData.useLegacyBottomAndRightAnchors;
     }
 
-    override updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
-      if (oldBehaviorData.leftEdgeAnchor !== newBehaviorData.leftEdgeAnchor) {
-        this._leftEdgeAnchor = newBehaviorData.leftEdgeAnchor;
+    override applyBehaviorOverriding(behaviorData): boolean {
+      if (behaviorData.leftEdgeAnchor !== undefined) {
+        this._leftEdgeAnchor = behaviorData.leftEdgeAnchor;
       }
-      if (oldBehaviorData.rightEdgeAnchor !== newBehaviorData.rightEdgeAnchor) {
-        this._rightEdgeAnchor = newBehaviorData.rightEdgeAnchor;
+      if (behaviorData.rightEdgeAnchor !== undefined) {
+        this._rightEdgeAnchor = behaviorData.rightEdgeAnchor;
       }
-      if (oldBehaviorData.topEdgeAnchor !== newBehaviorData.topEdgeAnchor) {
-        this._topEdgeAnchor = newBehaviorData.topEdgeAnchor;
+      if (behaviorData.topEdgeAnchor !== undefined) {
+        this._topEdgeAnchor = behaviorData.topEdgeAnchor;
       }
-      if (
-        oldBehaviorData.bottomEdgeAnchor !== newBehaviorData.bottomEdgeAnchor
-      ) {
-        this._bottomEdgeAnchor = newBehaviorData.bottomEdgeAnchor;
+      if (behaviorData.bottomEdgeAnchor !== undefined) {
+        this._bottomEdgeAnchor = behaviorData.bottomEdgeAnchor;
       }
-      if (
-        oldBehaviorData.useLegacyTrajectory !==
-        newBehaviorData.useLegacyTrajectory
-      ) {
+      if (behaviorData.useLegacyTrajectory !== undefined) {
         this._useLegacyBottomAndRightAnchors =
-          newBehaviorData.useLegacyBottomAndRightAnchors;
+          behaviorData.useLegacyBottomAndRightAnchors;
       }
-      if (
-        oldBehaviorData.relativeToOriginalWindowSize !==
-        newBehaviorData.relativeToOriginalWindowSize
-      ) {
+      if (behaviorData.relativeToOriginalWindowSize !== undefined) {
         return false;
       }
       return true;
diff --git a/Extensions/AnchorBehavior/tests/AnchorRuntimeBehaviorInCustomObject.spec.js b/Extensions/AnchorBehavior/tests/AnchorRuntimeBehaviorInCustomObject.spec.js
index aaacc7221..8cc51270a 100644
--- a/Extensions/AnchorBehavior/tests/AnchorRuntimeBehaviorInCustomObject.spec.js
+++ b/Extensions/AnchorBehavior/tests/AnchorRuntimeBehaviorInCustomObject.spec.js
@@ -1,6 +1,6 @@
 // @ts-check
 describe('gdjs.AnchorRuntimeBehavior', () => {
-  it('can fill a custom object with an child', async () => {
+  it('can fill a custom object with a child', async () => {
     const runtimeGame = await gdjs.getPixiRuntimeGameWithAssets();
     const runtimeScene = new gdjs.TestRuntimeScene(runtimeGame);
     // The corresponding event-based object declaration is done by
@@ -44,4 +44,109 @@ describe('gdjs.AnchorRuntimeBehavior', () => {
     expect(childObject.getWidth()).to.equal(2000);
     expect(childObject.getHeight()).to.equal(3000);
   });
+
+  it('can anchor 2 instances of the same object left and right', async () => {
+    const runtimeGame = await gdjs.getPixiRuntimeGameWithAssets({
+      customObjectInstances: [
+        {
+          angle: 0,
+          customSize: true,
+          height: 64,
+          layer: '',
+          name: 'MySprite',
+          persistentUuid: '668db48d-4e12-4b6f-aa6b-f73b74bf608e',
+          width: 32,
+          x: 0,
+          y: 0,
+          zOrder: 1,
+          numberProperties: [],
+          stringProperties: [],
+          initialVariables: [],
+          behaviorOverridings: [
+            // Magnet on the left
+            {
+              name: 'AnchorBehavior',
+              type: 'AnchorBehavior::AnchorBehavior',
+              rightEdgeAnchor: 0,
+            },
+          ],
+        },
+        {
+          angle: 0,
+          customSize: true,
+          height: 64,
+          layer: '',
+          name: 'MySprite',
+          persistentUuid: '668db48d-4e12-4b6f-aa6b-f73b74bf608e',
+          width: 32,
+          x: 32,
+          y: 0,
+          zOrder: 1,
+          numberProperties: [],
+          stringProperties: [],
+          initialVariables: [],
+          behaviorOverridings: [
+            // Magnet on the right
+            {
+              name: 'AnchorBehavior',
+              type: 'AnchorBehavior::AnchorBehavior',
+              leftEdgeAnchor: 0,
+            },
+          ],
+        },
+      ],
+    });
+    const runtimeScene = new gdjs.TestRuntimeScene(runtimeGame);
+    // The corresponding event-based object declaration is done by
+    // getPixiRuntimeGame.
+    const customObject = new gdjs.CustomRuntimeObject2D(runtimeScene, {
+      name: 'MyCustomObject',
+      type: 'MyExtension::MyLayoutedEventsBasedObject',
+      variant: '',
+      variables: [],
+      behaviors: [],
+      effects: [],
+      content: {},
+      childrenContent: {},
+      isInnerAreaFollowingParentSize: false,
+    });
+    runtimeScene.addObject(customObject);
+    customObject.setPosition(500, 250);
+
+    const childObjects = customObject
+      .getChildrenContainer()
+      .getObjects('MySprite');
+    if (!childObjects || childObjects.length === 0) {
+      throw new Error("Can't get child objects.");
+    }
+    const leftChildObject = childObjects[0];
+    const rightChildObject = childObjects[1];
+
+    runtimeScene.renderAndStep(1000 / 60);
+
+    // The child object keeps its initial location.
+    expect(leftChildObject.getX()).to.equal(0);
+    expect(leftChildObject.getY()).to.equal(0);
+    expect(leftChildObject.getWidth()).to.equal(32);
+    expect(leftChildObject.getHeight()).to.equal(64);
+
+    expect(rightChildObject.getX()).to.equal(32);
+    expect(rightChildObject.getY()).to.equal(0);
+    expect(rightChildObject.getWidth()).to.equal(32);
+    expect(rightChildObject.getHeight()).to.equal(64);
+
+    customObject.setWidth(200);
+    customObject.setHeight(300);
+    runtimeScene.renderAndStep(1000 / 60);
+
+    expect(leftChildObject.getX()).to.equal(0);
+    expect(leftChildObject.getY()).to.equal(0);
+    expect(leftChildObject.getWidth()).to.equal(32);
+    expect(leftChildObject.getHeight()).to.equal(300);
+
+    expect(rightChildObject.getX()).to.equal(32 + 200 - 64);
+    expect(rightChildObject.getY()).to.equal(0);
+    expect(rightChildObject.getWidth()).to.equal(32);
+    expect(rightChildObject.getHeight()).to.equal(300);
+  });
 });
diff --git a/Extensions/BBText/bbtextruntimeobject.ts b/Extensions/BBText/bbtextruntimeobject.ts
index b73b1a0aa..05437b713 100644
--- a/Extensions/BBText/bbtextruntimeobject.ts
+++ b/Extensions/BBText/bbtextruntimeobject.ts
@@ -87,9 +87,10 @@ namespace gdjs {
      */
     constructor(
       instanceContainer: gdjs.RuntimeInstanceContainer,
-      objectData: BBTextObjectData
+      objectData: BBTextObjectData,
+      instanceData?: InstanceData
     ) {
-      super(instanceContainer, objectData);
+      super(instanceContainer, objectData, instanceData);
       // @ts-ignore - parseFloat should not be required, but GDevelop 5.0 beta 92 and below were storing it as a string.
       this._opacity = parseFloat(objectData.content.opacity);
       this._text = objectData.content.text;
diff --git a/Extensions/BitmapText/bitmaptextruntimeobject.ts b/Extensions/BitmapText/bitmaptextruntimeobject.ts
index a4177ccc1..9fdf1ce01 100644
--- a/Extensions/BitmapText/bitmaptextruntimeobject.ts
+++ b/Extensions/BitmapText/bitmaptextruntimeobject.ts
@@ -88,9 +88,10 @@ namespace gdjs {
      */
     constructor(
       instanceContainer: gdjs.RuntimeInstanceContainer,
-      objectData: BitmapTextObjectData
+      objectData: BitmapTextObjectData,
+      instanceData?: InstanceData
     ) {
-      super(instanceContainer, objectData);
+      super(instanceContainer, objectData, instanceData);
 
       this._opacity = objectData.content.opacity;
       this._text = objectData.content.text;
diff --git a/Extensions/DestroyOutsideBehavior/destroyoutsideruntimebehavior.ts b/Extensions/DestroyOutsideBehavior/destroyoutsideruntimebehavior.ts
index 0016843d4..590d3b957 100644
--- a/Extensions/DestroyOutsideBehavior/destroyoutsideruntimebehavior.ts
+++ b/Extensions/DestroyOutsideBehavior/destroyoutsideruntimebehavior.ts
@@ -24,15 +24,12 @@ namespace gdjs {
       this._hasBeenOnScreen = false;
     }
 
-    updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
-      if (oldBehaviorData.extraBorder !== newBehaviorData.extraBorder) {
-        this._extraBorder = newBehaviorData.extraBorder;
+    override applyBehaviorOverriding(behaviorData): boolean {
+      if (behaviorData.extraBorder !== undefined) {
+        this._extraBorder = behaviorData.extraBorder;
       }
-      if (
-        oldBehaviorData.unseenGraceDistance !==
-        newBehaviorData.unseenGraceDistance
-      ) {
-        this._unseenGraceDistance = newBehaviorData.unseenGraceDistance;
+      if (behaviorData.unseenGraceDistance !== undefined) {
+        this._unseenGraceDistance = behaviorData.unseenGraceDistance;
       }
       return true;
     }
diff --git a/Extensions/DraggableBehavior/draggableruntimebehavior.ts b/Extensions/DraggableBehavior/draggableruntimebehavior.ts
index 7cf552fa2..330b55b10 100644
--- a/Extensions/DraggableBehavior/draggableruntimebehavior.ts
+++ b/Extensions/DraggableBehavior/draggableruntimebehavior.ts
@@ -27,7 +27,7 @@ namespace gdjs {
       this._checkCollisionMask = behaviorData.checkCollisionMask ? true : false;
     }
 
-    updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
+    override applyBehaviorOverriding(behaviorData): boolean {
       // Nothing to update.
       return true;
     }
diff --git a/Extensions/ExampleJsExtension/dummyruntimebehavior.ts b/Extensions/ExampleJsExtension/dummyruntimebehavior.ts
index 29d9e0932..1435472a7 100644
--- a/Extensions/ExampleJsExtension/dummyruntimebehavior.ts
+++ b/Extensions/ExampleJsExtension/dummyruntimebehavior.ts
@@ -26,9 +26,9 @@ namespace gdjs {
       logger.log('DummyRuntimeBehavior was created for object:', owner);
     }
 
-    updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
-      if (oldBehaviorData.property1 !== newBehaviorData.property1) {
-        this._textToSet = newBehaviorData.property1;
+    override applyBehaviorOverriding(behaviorData): boolean {
+      if (behaviorData.property1 !== undefined) {
+        this._textToSet = behaviorData.property1;
       }
 
       // Return true to specify that the new behavior data have been applied
diff --git a/Extensions/ExampleJsExtension/dummyruntimeobject.ts b/Extensions/ExampleJsExtension/dummyruntimeobject.ts
index f0214953e..bc45c1651 100644
--- a/Extensions/ExampleJsExtension/dummyruntimeobject.ts
+++ b/Extensions/ExampleJsExtension/dummyruntimeobject.ts
@@ -15,9 +15,13 @@ namespace gdjs {
     // @ts-expect-error ts-migrate(2564) FIXME: Property 'opacity' has no initializer and is not d... Remove this comment to see the full error message
     opacity: float;
 
-    constructor(instanceContainer: gdjs.RuntimeInstanceContainer, objectData) {
+    constructor(
+      instanceContainer: gdjs.RuntimeInstanceContainer,
+      objectData,
+      instanceData?: InstanceData
+    ) {
       // *ALWAYS* call the base gdjs.RuntimeObject constructor.
-      super(instanceContainer, objectData);
+      super(instanceContainer, objectData, instanceData);
       this._property1 = objectData.content.property1;
       this._renderer = new gdjs.DummyRuntimeObjectRenderer(
         this,
diff --git a/Extensions/ExampleJsExtension/dummywithshareddataruntimebehavior.ts b/Extensions/ExampleJsExtension/dummywithshareddataruntimebehavior.ts
index adad4cf62..75f07dd8f 100644
--- a/Extensions/ExampleJsExtension/dummywithshareddataruntimebehavior.ts
+++ b/Extensions/ExampleJsExtension/dummywithshareddataruntimebehavior.ts
@@ -32,9 +32,9 @@ namespace gdjs {
       logger.log('The shared data are:', sharedData);
     }
 
-    updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
-      if (oldBehaviorData.property1 !== newBehaviorData.property1) {
-        this._textToSet = newBehaviorData.property1;
+    override applyBehaviorOverriding(behaviorData): boolean {
+      if (behaviorData.property1 !== undefined) {
+        this._textToSet = behaviorData.property1;
       }
 
       // Return true to specify that the new behavior data have been applied
diff --git a/Extensions/Lighting/lightruntimeobject.ts b/Extensions/Lighting/lightruntimeobject.ts
index 1e0e7c642..a278f064b 100644
--- a/Extensions/Lighting/lightruntimeobject.ts
+++ b/Extensions/Lighting/lightruntimeobject.ts
@@ -52,9 +52,10 @@ namespace gdjs {
 
     constructor(
       runtimeScene: gdjs.RuntimeScene,
-      lightObjectData: LightObjectData
+      lightObjectData: LightObjectData,
+      instanceData?: InstanceData
     ) {
-      super(runtimeScene, lightObjectData);
+      super(runtimeScene, lightObjectData, instanceData);
       this._radius =
         lightObjectData.content.radius > 0 ? lightObjectData.content.radius : 1;
       this._color = gdjs.rgbOrHexToRGBColor(lightObjectData.content.color);
diff --git a/Extensions/LinkedObjects/tests/linkedobjects.spec.js b/Extensions/LinkedObjects/tests/linkedobjects.spec.js
index 44b5614c0..9a07fa7c4 100644
--- a/Extensions/LinkedObjects/tests/linkedobjects.spec.js
+++ b/Extensions/LinkedObjects/tests/linkedobjects.spec.js
@@ -54,76 +54,112 @@ describe('gdjs.LinksManager', function () {
 
     const manager = gdjs.LinksManager.getManager(runtimeScene);
 
-    const object1A = new gdjs.RuntimeObject(runtimeScene, {
-      name: object1Names[0],
-      type: '',
-      behaviors: [],
-      variables: [],
-      effects: [],
-    });
-    const object1B = new gdjs.RuntimeObject(runtimeScene, {
-      name: object1Names[1],
-      type: '',
-      behaviors: [],
-      variables: [],
-      effects: [],
-    });
+    const object1A = new gdjs.RuntimeObject(
+      runtimeScene,
+      {
+        name: object1Names[0],
+        type: '',
+        behaviors: [],
+        variables: [],
+        effects: [],
+      },
+      undefined
+    );
+    const object1B = new gdjs.RuntimeObject(
+      runtimeScene,
+      {
+        name: object1Names[1],
+        type: '',
+        behaviors: [],
+        variables: [],
+        effects: [],
+      },
+      undefined
+    );
 
-    const object1C = new gdjs.RuntimeObject(runtimeScene, {
-      name: object1Names[2],
-      type: '',
-      behaviors: [],
-      variables: [],
-      effects: [],
-    });
+    const object1C = new gdjs.RuntimeObject(
+      runtimeScene,
+      {
+        name: object1Names[2],
+        type: '',
+        behaviors: [],
+        variables: [],
+        effects: [],
+      },
+      undefined
+    );
 
-    const object2A = new gdjs.RuntimeObject(runtimeScene, {
-      name: object2Names[0],
-      type: '',
-      behaviors: [],
-      variables: [],
-      effects: [],
-    });
+    const object2A = new gdjs.RuntimeObject(
+      runtimeScene,
+      {
+        name: object2Names[0],
+        type: '',
+        behaviors: [],
+        variables: [],
+        effects: [],
+      },
+      undefined
+    );
 
-    const object2B = new gdjs.RuntimeObject(runtimeScene, {
-      name: object2Names[1],
-      type: '',
-      behaviors: [],
-      variables: [],
-      effects: [],
-    });
+    const object2B = new gdjs.RuntimeObject(
+      runtimeScene,
+      {
+        name: object2Names[1],
+        type: '',
+        behaviors: [],
+        variables: [],
+        effects: [],
+      },
+      undefined
+    );
 
-    const object2C = new gdjs.RuntimeObject(runtimeScene, {
-      name: object2Names[2],
-      type: '',
-      behaviors: [],
-      variables: [],
-      effects: [],
-    });
+    const object2C = new gdjs.RuntimeObject(
+      runtimeScene,
+      {
+        name: object2Names[2],
+        type: '',
+        behaviors: [],
+        variables: [],
+        effects: [],
+      },
+      undefined
+    );
 
-    const object3A = new gdjs.RuntimeObject(runtimeScene, {
-      name: object3Names[0],
-      type: '',
-      behaviors: [],
-      variables: [],
-      effects: [],
-    });
+    const object3A = new gdjs.RuntimeObject(
+      runtimeScene,
+      {
+        name: object3Names[0],
+        type: '',
+        behaviors: [],
+        variables: [],
+        effects: [],
+      },
+      undefined
+    );
 
-    const object3B = new gdjs.RuntimeObject(runtimeScene, {
-      name: object3Names[1],
-      type: '',
-      behaviors: [],
-      variables: [],
-      effects: [],
-    });
+    const object3B = new gdjs.RuntimeObject(
+      runtimeScene,
+      {
+        name: object3Names[1],
+        type: '',
+        behaviors: [],
+        variables: [],
+        effects: [],
+      },
+      undefined
+    );
 
-    const object3C = new gdjs.RuntimeObject(runtimeScene, {
-      name: object3Names[2],
-      type: '',
-      behaviors: [],
-      variables: [],
-      effects: [],
-    });
+    const object3C = new gdjs.RuntimeObject(
+      runtimeScene,
+      {
+        name: object3Names[2],
+        type: '',
+        behaviors: [],
+        variables: [],
+        effects: [],
+      },
+      undefined
+    );
 
     runtimeScene.addObject(object1A);
     runtimeScene.addObject(object1B);
diff --git a/Extensions/PanelSpriteObject/panelspriteruntimeobject.ts b/Extensions/PanelSpriteObject/panelspriteruntimeobject.ts
index 1e33da4d6..813c9f3b3 100644
--- a/Extensions/PanelSpriteObject/panelspriteruntimeobject.ts
+++ b/Extensions/PanelSpriteObject/panelspriteruntimeobject.ts
@@ -74,9 +74,10 @@ namespace gdjs {
      */
     constructor(
       instanceContainer: gdjs.RuntimeInstanceContainer,
-      panelSpriteObjectData: PanelSpriteObjectData
+      panelSpriteObjectData: PanelSpriteObjectData,
+      instanceData?: InstanceData
     ) {
-      super(instanceContainer, panelSpriteObjectData);
+      super(instanceContainer, panelSpriteObjectData, instanceData);
       this._objectData = panelSpriteObjectData;
       this._rBorder = panelSpriteObjectData.rightMargin;
       this._lBorder = panelSpriteObjectData.leftMargin;
diff --git a/Extensions/ParticleSystem/particleemitterobject.ts b/Extensions/ParticleSystem/particleemitterobject.ts
index 62f99b351..cae8cca61 100644
--- a/Extensions/ParticleSystem/particleemitterobject.ts
+++ b/Extensions/ParticleSystem/particleemitterobject.ts
@@ -180,9 +180,10 @@ namespace gdjs {
      */
     constructor(
       instanceContainer: gdjs.RuntimeInstanceContainer,
-      particleObjectData: ParticleEmitterObjectData
+      particleObjectData: ParticleEmitterObjectData,
+      instanceData?: InstanceData
     ) {
-      super(instanceContainer, particleObjectData);
+      super(instanceContainer, particleObjectData, instanceData);
       this._renderer = new gdjs.ParticleEmitterObjectRenderer(
         instanceContainer,
         this,
diff --git a/Extensions/PathfindingBehavior/pathfindingobstacleruntimebehavior.ts b/Extensions/PathfindingBehavior/pathfindingobstacleruntimebehavior.ts
index 4b3493d66..94852e75c 100644
--- a/Extensions/PathfindingBehavior/pathfindingobstacleruntimebehavior.ts
+++ b/Extensions/PathfindingBehavior/pathfindingobstacleruntimebehavior.ts
@@ -126,12 +126,12 @@ namespace gdjs {
       //The owner is not yet fully constructed.
     }
 
-    updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
-      if (oldBehaviorData.impassable !== newBehaviorData.impassable) {
-        this.setImpassable(newBehaviorData.impassable);
+    override applyBehaviorOverriding(behaviorData): boolean {
+      if (behaviorData.impassable !== undefined) {
+        this.setImpassable(behaviorData.impassable);
       }
-      if (oldBehaviorData.cost !== newBehaviorData.cost) {
-        this.setCost(newBehaviorData.cost);
+      if (behaviorData.cost !== undefined) {
+        this.setCost(behaviorData.cost);
       }
       return true;
     }
diff --git a/Extensions/PathfindingBehavior/pathfindingruntimebehavior.ts b/Extensions/PathfindingBehavior/pathfindingruntimebehavior.ts
index bb84b2689..045b0f9fd 100644
--- a/Extensions/PathfindingBehavior/pathfindingruntimebehavior.ts
+++ b/Extensions/PathfindingBehavior/pathfindingruntimebehavior.ts
@@ -93,45 +93,42 @@ namespace gdjs {
       );
     }
 
-    updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
-      if (oldBehaviorData.allowDiagonals !== newBehaviorData.allowDiagonals) {
-        this.allowDiagonals(newBehaviorData.allowDiagonals);
+    override applyBehaviorOverriding(behaviorData): boolean {
+      if (behaviorData.allowDiagonals !== undefined) {
+        this.allowDiagonals(behaviorData.allowDiagonals);
       }
-      if (oldBehaviorData.acceleration !== newBehaviorData.acceleration) {
-        this.setAcceleration(newBehaviorData.acceleration);
+      if (behaviorData.acceleration !== undefined) {
+        this.setAcceleration(behaviorData.acceleration);
       }
-      if (oldBehaviorData.maxSpeed !== newBehaviorData.maxSpeed) {
-        this.setMaxSpeed(newBehaviorData.maxSpeed);
+      if (behaviorData.maxSpeed !== undefined) {
+        this.setMaxSpeed(behaviorData.maxSpeed);
       }
-      if (oldBehaviorData.angularMaxSpeed !== newBehaviorData.angularMaxSpeed) {
-        this.setAngularMaxSpeed(newBehaviorData.angularMaxSpeed);
+      if (behaviorData.angularMaxSpeed !== undefined) {
+        this.setAngularMaxSpeed(behaviorData.angularMaxSpeed);
       }
-      if (oldBehaviorData.rotateObject !== newBehaviorData.rotateObject) {
-        this.setRotateObject(newBehaviorData.rotateObject);
+      if (behaviorData.rotateObject !== undefined) {
+        this.setRotateObject(behaviorData.rotateObject);
       }
-      if (oldBehaviorData.angleOffset !== newBehaviorData.angleOffset) {
-        this.setAngleOffset(newBehaviorData.angleOffset);
+      if (behaviorData.angleOffset !== undefined) {
+        this.setAngleOffset(behaviorData.angleOffset);
       }
-      if (oldBehaviorData.cellWidth !== newBehaviorData.cellWidth) {
-        this.setCellWidth(newBehaviorData.cellWidth);
+      if (behaviorData.cellWidth !== undefined) {
+        this.setCellWidth(behaviorData.cellWidth);
       }
-      if (oldBehaviorData.cellHeight !== newBehaviorData.cellHeight) {
-        this.setCellHeight(newBehaviorData.cellHeight);
+      if (behaviorData.cellHeight !== undefined) {
+        this.setCellHeight(behaviorData.cellHeight);
       }
-      if (oldBehaviorData.gridOffsetX !== newBehaviorData.gridOffsetX) {
-        this._gridOffsetX = newBehaviorData.gridOffsetX;
+      if (behaviorData.gridOffsetX !== undefined) {
+        this._gridOffsetX = behaviorData.gridOffsetX;
       }
-      if (oldBehaviorData.gridOffsetY !== newBehaviorData.gridOffsetY) {
-        this._gridOffsetY = newBehaviorData.gridOffsetY;
+      if (behaviorData.gridOffsetY !== undefined) {
+        this._gridOffsetY = behaviorData.gridOffsetY;
       }
-      if (oldBehaviorData.extraBorder !== newBehaviorData.extraBorder) {
-        this.setExtraBorder(newBehaviorData.extraBorder);
+      if (behaviorData.extraBorder !== undefined) {
+        this.setExtraBorder(behaviorData.extraBorder);
       }
-      if (
-        oldBehaviorData.smoothingMaxCellGap !==
-        newBehaviorData.smoothingMaxCellGap
-      ) {
-        this._smoothingMaxCellGap = newBehaviorData.smoothingMaxCellGap;
+      if (behaviorData.smoothingMaxCellGap !== undefined) {
+        this._smoothingMaxCellGap = behaviorData.smoothingMaxCellGap;
       }
       return true;
     }
diff --git a/Extensions/PathfindingBehavior/tests/FrameRatePathfindingRuntimeBehavior.spec.js b/Extensions/PathfindingBehavior/tests/FrameRatePathfindingRuntimeBehavior.spec.js
index 87049ceff..c96a140fd 100644
--- a/Extensions/PathfindingBehavior/tests/FrameRatePathfindingRuntimeBehavior.spec.js
+++ b/Extensions/PathfindingBehavior/tests/FrameRatePathfindingRuntimeBehavior.spec.js
@@ -62,29 +62,33 @@ describe('gdjs.PathfindingRuntimeBehavior', function () {
     };
 
     const addPlayer = (runtimeScene, allowDiagonals) => {
-      const player = new gdjs.RuntimeObject(runtimeScene, {
-        name: 'player',
-        type: '',
-        behaviors: [
-          {
-            type: 'PathfindingBehavior::PathfindingBehavior',
-            name: 'auto1',
-            // @ts-ignore - properties are not typed
-            allowDiagonals: allowDiagonals,
-            acceleration: 400,
-            maxSpeed: 200,
-            angularMaxSpeed: 180,
-            rotateObject: false,
-            angleOffset: 0,
-            cellWidth: 20,
-            cellHeight: 20,
-            extraBorder: 0,
-            collisionMethod: true,
-          },
-        ],
-        effects: [],
-        variables: [],
-      });
+      const player = new gdjs.RuntimeObject(
+        runtimeScene,
+        {
+          name: 'player',
+          type: '',
+          behaviors: [
+            {
+              type: 'PathfindingBehavior::PathfindingBehavior',
+              name: 'auto1',
+              // @ts-ignore - properties are not typed
+              allowDiagonals: allowDiagonals,
+              acceleration: 400,
+              maxSpeed: 200,
+              angularMaxSpeed: 180,
+              rotateObject: false,
+              angleOffset: 0,
+              cellWidth: 20,
+              cellHeight: 20,
+              extraBorder: 0,
+              collisionMethod: true,
+            },
+          ],
+          effects: [],
+          variables: [],
+        },
+        undefined
+      );
       player.getWidth = function () {
         return 90;
       };
@@ -96,20 +100,24 @@ describe('gdjs.PathfindingRuntimeBehavior', function () {
     };
 
     const addObstacle = (runtimeScene) => {
-      const obstacle = new gdjs.RuntimeObject(runtimeScene, {
-        name: 'obstacle',
-        type: '',
-        behaviors: [
-          {
-            type: 'PathfindingBehavior::PathfindingObstacleBehavior',
-            // @ts-ignore - properties are not typed
-            impassable: true,
-            cost: 2,
-          },
-        ],
-        effects: [],
-        variables: [],
-      });
+      const obstacle = new gdjs.RuntimeObject(
+        runtimeScene,
+        {
+          name: 'obstacle',
+          type: '',
+          behaviors: [
+            {
+              type: 'PathfindingBehavior::PathfindingObstacleBehavior',
+              // @ts-ignore - properties are not typed
+              impassable: true,
+              cost: 2,
+            },
+          ],
+          effects: [],
+          variables: [],
+        },
+        undefined
+      );
       obstacle.getWidth = function () {
         return 100;
       };
diff --git a/Extensions/PathfindingBehavior/tests/commonpathfindingruntimebehavior.spec.js b/Extensions/PathfindingBehavior/tests/commonpathfindingruntimebehavior.spec.js
index 28fbe6e87..3ca6ff37c 100644
--- a/Extensions/PathfindingBehavior/tests/commonpathfindingruntimebehavior.spec.js
+++ b/Extensions/PathfindingBehavior/tests/commonpathfindingruntimebehavior.spec.js
@@ -65,30 +65,34 @@ describe('gdjs.PathfindingRuntimeBehavior', function () {
     };
 
     const addPlayer = (runtimeScene) => {
-      const player = new gdjs.RuntimeObject(runtimeScene, {
-        name: 'player',
-        type: '',
-        behaviors: [
-          {
-            type: 'PathfindingBehavior::PathfindingBehavior',
-            name: 'auto1',
-            // @ts-ignore - properties are not typed
-            allowDiagonals: allowDiagonals,
-            acceleration: 400,
-            maxSpeed: 200,
-            angularMaxSpeed: 180,
-            rotateObject: false,
-            angleOffset: 0,
-            cellWidth: 20,
-            cellHeight: 20,
-            extraBorder: 0,
-            smoothingMaxCellGap: smoothingMaxCellGap,
-            collisionMethod: collisionMethod,
-          },
-        ],
-        effects: [],
-        variables: [],
-      });
+      const player = new gdjs.RuntimeObject(
+        runtimeScene,
+        {
+          name: 'player',
+          type: '',
+          behaviors: [
+            {
+              type: 'PathfindingBehavior::PathfindingBehavior',
+              name: 'auto1',
+              // @ts-ignore - properties are not typed
+              allowDiagonals: allowDiagonals,
+              acceleration: 400,
+              maxSpeed: 200,
+              angularMaxSpeed: 180,
+              rotateObject: false,
+              angleOffset: 0,
+              cellWidth: 20,
+              cellHeight: 20,
+              extraBorder: 0,
+              smoothingMaxCellGap: smoothingMaxCellGap,
+              collisionMethod: collisionMethod,
+            },
+          ],
+          effects: [],
+          variables: [],
+        },
+        undefined
+      );
       player.getWidth = function () {
         return 90;
       };
@@ -100,20 +104,24 @@ describe('gdjs.PathfindingRuntimeBehavior', function () {
     };
 
     const addObstacle = (runtimeScene) => {
-      const obstacle = new gdjs.RuntimeObject(runtimeScene, {
-        name: 'obstacle',
-        type: '',
-        behaviors: [
-          {
-            type: 'PathfindingBehavior::PathfindingObstacleBehavior',
-            // @ts-ignore - properties are not typed
-            impassable: true,
-            cost: 2,
-          },
-        ],
-        effects: [],
-        variables: [],
-      });
+      const obstacle = new gdjs.RuntimeObject(
+        runtimeScene,
+        {
+          name: 'obstacle',
+          type: '',
+          behaviors: [
+            {
+              type: 'PathfindingBehavior::PathfindingObstacleBehavior',
+              // @ts-ignore - properties are not typed
+              impassable: true,
+              cost: 2,
+            },
+          ],
+          effects: [],
+          variables: [],
+        },
+        undefined
+      );
       obstacle.getWidth = function () {
         return 100;
       };
diff --git a/Extensions/Physics2Behavior/physics2runtimebehavior.ts b/Extensions/Physics2Behavior/physics2runtimebehavior.ts
index c6647d96c..3ac33586e 100644
--- a/Extensions/Physics2Behavior/physics2runtimebehavior.ts
+++ b/Extensions/Physics2Behavior/physics2runtimebehavior.ts
@@ -443,69 +443,69 @@ namespace gdjs {
       return tempb2Vec2Sec;
     }
 
-    updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
-      if (oldBehaviorData.bullet !== newBehaviorData.bullet) {
-        this.setBullet(newBehaviorData.bullet);
+    override applyBehaviorOverriding(behaviorData): boolean {
+      if (behaviorData.bullet !== undefined) {
+        this.setBullet(behaviorData.bullet);
       }
-      if (oldBehaviorData.fixedRotation !== newBehaviorData.fixedRotation) {
-        this.setFixedRotation(newBehaviorData.fixedRotation);
+      if (behaviorData.fixedRotation !== undefined) {
+        this.setFixedRotation(behaviorData.fixedRotation);
       }
-      if (oldBehaviorData.canSleep !== newBehaviorData.canSleep) {
-        this.setSleepingAllowed(newBehaviorData.canSleep);
+      if (behaviorData.canSleep !== undefined) {
+        this.setSleepingAllowed(behaviorData.canSleep);
       }
-      if (oldBehaviorData.shapeDimensionA !== newBehaviorData.shapeDimensionA) {
-        this.shapeDimensionA = newBehaviorData.shapeDimensionA;
+      if (behaviorData.shapeDimensionA !== undefined) {
+        this.shapeDimensionA = behaviorData.shapeDimensionA;
         this.recreateShape();
       }
-      if (oldBehaviorData.shapeDimensionB !== newBehaviorData.shapeDimensionB) {
-        this.shapeDimensionB = newBehaviorData.shapeDimensionB;
+      if (behaviorData.shapeDimensionB !== undefined) {
+        this.shapeDimensionB = behaviorData.shapeDimensionB;
         this.recreateShape();
       }
-      if (oldBehaviorData.shapeOffsetX !== newBehaviorData.shapeOffsetX) {
-        this.shapeOffsetX = newBehaviorData.shapeOffsetX;
+      if (behaviorData.shapeOffsetX !== undefined) {
+        this.shapeOffsetX = behaviorData.shapeOffsetX;
         this.recreateShape();
       }
-      if (oldBehaviorData.shapeOffsetY !== newBehaviorData.shapeOffsetY) {
-        this.shapeOffsetY = newBehaviorData.shapeOffsetY;
+      if (behaviorData.shapeOffsetY !== undefined) {
+        this.shapeOffsetY = behaviorData.shapeOffsetY;
         this.recreateShape();
       }
-      if (oldBehaviorData.polygonOrigin !== newBehaviorData.polygonOrigin) {
-        this.polygonOrigin = newBehaviorData.polygonOrigin;
+      if (behaviorData.polygonOrigin !== undefined) {
+        this.polygonOrigin = behaviorData.polygonOrigin;
         this.recreateShape();
       }
-      if (oldBehaviorData.density !== newBehaviorData.density) {
-        this.setDensity(newBehaviorData.density);
+      if (behaviorData.density !== undefined) {
+        this.setDensity(behaviorData.density);
       }
-      if (oldBehaviorData.friction !== newBehaviorData.friction) {
-        this.setFriction(newBehaviorData.friction);
+      if (behaviorData.friction !== undefined) {
+        this.setFriction(behaviorData.friction);
       }
-      if (oldBehaviorData.restitution !== newBehaviorData.restitution) {
-        this.setRestitution(newBehaviorData.restitution);
+      if (behaviorData.restitution !== undefined) {
+        this.setRestitution(behaviorData.restitution);
       }
-      if (oldBehaviorData.linearDamping !== newBehaviorData.linearDamping) {
-        this.setLinearDamping(newBehaviorData.linearDamping);
+      if (behaviorData.linearDamping !== undefined) {
+        this.setLinearDamping(behaviorData.linearDamping);
       }
-      if (oldBehaviorData.angularDamping !== newBehaviorData.angularDamping) {
-        this.setAngularDamping(newBehaviorData.angularDamping);
+      if (behaviorData.angularDamping !== undefined) {
+        this.setAngularDamping(behaviorData.angularDamping);
       }
-      if (oldBehaviorData.gravityScale !== newBehaviorData.gravityScale) {
-        this.setGravityScale(newBehaviorData.gravityScale);
+      if (behaviorData.gravityScale !== undefined) {
+        this.setGravityScale(behaviorData.gravityScale);
       }
 
       // TODO: make these properties updatable.
-      if (oldBehaviorData.layers !== newBehaviorData.layers) {
+      if (behaviorData.layers !== undefined) {
         return false;
       }
-      if (oldBehaviorData.masks !== newBehaviorData.masks) {
+      if (behaviorData.masks !== undefined) {
         return false;
       }
-      if (oldBehaviorData.vertices !== newBehaviorData.vertices) {
+      if (behaviorData.vertices !== undefined) {
         return false;
       }
-      if (oldBehaviorData.bodyType !== newBehaviorData.bodyType) {
+      if (behaviorData.bodyType !== undefined) {
         return false;
       }
-      if (oldBehaviorData.shape !== newBehaviorData.shape) {
+      if (behaviorData.shape !== undefined) {
         return false;
       }
       return true;
diff --git a/Extensions/Physics3DBehavior/Physics3DRuntimeBehavior.ts b/Extensions/Physics3DBehavior/Physics3DRuntimeBehavior.ts
index 0142cc8d6..daf0272e9 100644
--- a/Extensions/Physics3DBehavior/Physics3DRuntimeBehavior.ts
+++ b/Extensions/Physics3DBehavior/Physics3DRuntimeBehavior.ts
@@ -459,54 +459,54 @@ namespace gdjs {
       return tempQuat;
     }
 
-    override updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
-      if (oldBehaviorData.bullet !== newBehaviorData.bullet) {
-        this.setBullet(newBehaviorData.bullet);
+    override applyBehaviorOverriding(behaviorData): boolean {
+      if (behaviorData.bullet !== undefined) {
+        this.setBullet(behaviorData.bullet);
       }
-      if (oldBehaviorData.fixedRotation !== newBehaviorData.fixedRotation) {
-        this.setFixedRotation(newBehaviorData.fixedRotation);
+      if (behaviorData.fixedRotation !== undefined) {
+        this.setFixedRotation(behaviorData.fixedRotation);
       }
-      if (oldBehaviorData.shapeDimensionA !== newBehaviorData.shapeDimensionA) {
-        this.shapeDimensionA = newBehaviorData.shapeDimensionA;
+      if (behaviorData.shapeDimensionA !== undefined) {
+        this.shapeDimensionA = behaviorData.shapeDimensionA;
         this._needToRecreateShape = true;
       }
-      if (oldBehaviorData.shapeDimensionB !== newBehaviorData.shapeDimensionB) {
-        this.shapeDimensionB = newBehaviorData.shapeDimensionB;
+      if (behaviorData.shapeDimensionB !== undefined) {
+        this.shapeDimensionB = behaviorData.shapeDimensionB;
         this._needToRecreateShape = true;
       }
-      if (oldBehaviorData.density !== newBehaviorData.density) {
-        this.setDensity(newBehaviorData.density);
+      if (behaviorData.density !== undefined) {
+        this.setDensity(behaviorData.density);
       }
-      if (oldBehaviorData.friction !== newBehaviorData.friction) {
-        this.setFriction(newBehaviorData.friction);
+      if (behaviorData.friction !== undefined) {
+        this.setFriction(behaviorData.friction);
       }
-      if (oldBehaviorData.restitution !== newBehaviorData.restitution) {
-        this.setRestitution(newBehaviorData.restitution);
+      if (behaviorData.restitution !== undefined) {
+        this.setRestitution(behaviorData.restitution);
       }
-      if (oldBehaviorData.linearDamping !== newBehaviorData.linearDamping) {
-        this.setLinearDamping(newBehaviorData.linearDamping);
+      if (behaviorData.linearDamping !== undefined) {
+        this.setLinearDamping(behaviorData.linearDamping);
       }
-      if (oldBehaviorData.angularDamping !== newBehaviorData.angularDamping) {
-        this.setAngularDamping(newBehaviorData.angularDamping);
+      if (behaviorData.angularDamping !== undefined) {
+        this.setAngularDamping(behaviorData.angularDamping);
       }
-      if (oldBehaviorData.gravityScale !== newBehaviorData.gravityScale) {
-        this.setGravityScale(newBehaviorData.gravityScale);
+      if (behaviorData.gravityScale !== undefined) {
+        this.setGravityScale(behaviorData.gravityScale);
       }
 
       // TODO: make these properties updatable.
-      if (oldBehaviorData.layers !== newBehaviorData.layers) {
+      if (behaviorData.layers !== undefined) {
         return false;
       }
-      if (oldBehaviorData.masks !== newBehaviorData.masks) {
+      if (behaviorData.masks !== undefined) {
         return false;
       }
-      if (oldBehaviorData.vertices !== newBehaviorData.vertices) {
+      if (behaviorData.vertices !== undefined) {
         return false;
       }
-      if (oldBehaviorData.bodyType !== newBehaviorData.bodyType) {
+      if (behaviorData.bodyType !== undefined) {
         return false;
       }
-      if (oldBehaviorData.shape !== newBehaviorData.shape) {
+      if (behaviorData.shape !== undefined) {
         return false;
       }
       return true;
diff --git a/Extensions/Physics3DBehavior/PhysicsCar3DRuntimeBehavior.ts b/Extensions/Physics3DBehavior/PhysicsCar3DRuntimeBehavior.ts
index 40179018c..6e66ec3a8 100644
--- a/Extensions/Physics3DBehavior/PhysicsCar3DRuntimeBehavior.ts
+++ b/Extensions/Physics3DBehavior/PhysicsCar3DRuntimeBehavior.ts
@@ -212,97 +212,78 @@ namespace gdjs {
       return this._physics3D;
     }
 
-    override updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
-      if (oldBehaviorData.steerAngleMax !== newBehaviorData.steerAngleMax) {
-        this.setSteerAngleMax(newBehaviorData.steerAngleMax);
+    override applyBehaviorOverriding(behaviorData): boolean {
+      if (behaviorData.steerAngleMax !== undefined) {
+        this.setSteerAngleMax(behaviorData.steerAngleMax);
       }
-      if (
-        oldBehaviorData.beginningSteerSpeed !==
-        newBehaviorData.beginningSteerSpeed
-      ) {
-        this.setBeginningSteerSpeed(newBehaviorData.beginningSteerSpeed);
+      if (behaviorData.beginningSteerSpeed !== undefined) {
+        this.setBeginningSteerSpeed(behaviorData.beginningSteerSpeed);
       }
-      if (oldBehaviorData.endSteerSpeed !== newBehaviorData.endSteerSpeed) {
-        this.setEndSteerSpeed(newBehaviorData.endSteerSpeed);
+      if (behaviorData.endSteerSpeed !== undefined) {
+        this.setEndSteerSpeed(behaviorData.endSteerSpeed);
       }
-      if (oldBehaviorData.engineTorqueMax !== newBehaviorData.engineTorqueMax) {
-        this.setEngineTorqueMax(newBehaviorData.engineTorqueMax);
+      if (behaviorData.engineTorqueMax !== undefined) {
+        this.setEngineTorqueMax(behaviorData.engineTorqueMax);
       }
-      if (oldBehaviorData.engineSpeedMax !== newBehaviorData.engineSpeedMax) {
-        this.setEngineSpeedMax(newBehaviorData.engineSpeedMax);
+      if (behaviorData.engineSpeedMax !== undefined) {
+        this.setEngineSpeedMax(behaviorData.engineSpeedMax);
       }
-      if (oldBehaviorData.engineInertia !== newBehaviorData.engineInertia) {
-        this.setEngineInertia(newBehaviorData.engineInertia);
+      if (behaviorData.engineInertia !== undefined) {
+        this.setEngineInertia(behaviorData.engineInertia);
       }
-      if (
-        oldBehaviorData.reverseGearRatio1 !== newBehaviorData.reverseGearRatio1
-      ) {
-        this.setGearRatio(-1, newBehaviorData.reverseGearRatio1);
+      if (behaviorData.reverseGearRatio1 !== undefined) {
+        this.setGearRatio(-1, behaviorData.reverseGearRatio1);
       }
-      if (oldBehaviorData.gearRatio1 !== newBehaviorData.gearRatio1) {
-        this.setGearRatio(1, newBehaviorData.gearRatio1);
+      if (behaviorData.gearRatio1 !== undefined) {
+        this.setGearRatio(1, behaviorData.gearRatio1);
       }
-      if (oldBehaviorData.gearRatio2 !== newBehaviorData.gearRatio2) {
-        this.setGearRatio(2, newBehaviorData.gearRatio2);
+      if (behaviorData.gearRatio2 !== undefined) {
+        this.setGearRatio(2, behaviorData.gearRatio2);
       }
-      if (oldBehaviorData.gearRatio3 !== newBehaviorData.gearRatio3) {
-        this.setGearRatio(3, newBehaviorData.gearRatio3);
+      if (behaviorData.gearRatio3 !== undefined) {
+        this.setGearRatio(3, behaviorData.gearRatio3);
       }
-      if (oldBehaviorData.gearRatio4 !== newBehaviorData.gearRatio4) {
-        this.setGearRatio(4, newBehaviorData.gearRatio4);
+      if (behaviorData.gearRatio4 !== undefined) {
+        this.setGearRatio(4, behaviorData.gearRatio4);
       }
-      if (oldBehaviorData.gearRatio5 !== newBehaviorData.gearRatio5) {
-        this.setGearRatio(5, newBehaviorData.gearRatio5);
+      if (behaviorData.gearRatio5 !== undefined) {
+        this.setGearRatio(5, behaviorData.gearRatio5);
       }
-      if (oldBehaviorData.gearRatio6 !== newBehaviorData.gearRatio6) {
-        this.setGearRatio(6, newBehaviorData.gearRatio6);
+      if (behaviorData.gearRatio6 !== undefined) {
+        this.setGearRatio(6, behaviorData.gearRatio6);
       }
-      if (
-        oldBehaviorData.backWheelOffsetX !== newBehaviorData.backWheelOffsetX
-      ) {
-        this.setBackWheelOffsetX(newBehaviorData.backWheelOffsetX);
+      if (behaviorData.backWheelOffsetX !== undefined) {
+        this.setBackWheelOffsetX(behaviorData.backWheelOffsetX);
       }
-      if (
-        oldBehaviorData.frontWheelOffsetX !== newBehaviorData.frontWheelOffsetX
-      ) {
-        this.setFrontWheelOffsetX(newBehaviorData.frontWheelOffsetX);
+      if (behaviorData.frontWheelOffsetX !== undefined) {
+        this.setFrontWheelOffsetX(behaviorData.frontWheelOffsetX);
       }
-      if (oldBehaviorData.wheelOffsetY !== newBehaviorData.wheelOffsetY) {
-        this.setWheelOffsetY(newBehaviorData.wheelOffsetY);
+      if (behaviorData.wheelOffsetY !== undefined) {
+        this.setWheelOffsetY(behaviorData.wheelOffsetY);
       }
-      if (oldBehaviorData.wheelOffsetZ !== newBehaviorData.wheelOffsetZ) {
-        this.setWheelOffsetZ(newBehaviorData.wheelOffsetZ);
+      if (behaviorData.wheelOffsetZ !== undefined) {
+        this.setWheelOffsetZ(behaviorData.wheelOffsetZ);
       }
-      if (oldBehaviorData.wheelRadius !== newBehaviorData.wheelRadius) {
-        this.setWheelRadius(newBehaviorData.wheelRadius);
+      if (behaviorData.wheelRadius !== undefined) {
+        this.setWheelRadius(behaviorData.wheelRadius);
       }
-      if (oldBehaviorData.wheelWidth !== newBehaviorData.wheelWidth) {
-        this.setWheelWidth(newBehaviorData.wheelWidth);
+      if (behaviorData.wheelWidth !== undefined) {
+        this.setWheelWidth(behaviorData.wheelWidth);
       }
-      if (oldBehaviorData.brakeTorqueMax !== newBehaviorData.brakeTorqueMax) {
-        this.setBrakeTorqueMax(newBehaviorData.brakeTorqueMax);
+      if (behaviorData.brakeTorqueMax !== undefined) {
+        this.setBrakeTorqueMax(behaviorData.brakeTorqueMax);
       }
-      if (
-        oldBehaviorData.handBrakeTorqueMax !==
-        newBehaviorData.handBrakeTorqueMax
-      ) {
-        this.setHandBrakeTorqueMax(newBehaviorData.handBrakeTorqueMax);
+      if (behaviorData.handBrakeTorqueMax !== undefined) {
+        this.setHandBrakeTorqueMax(behaviorData.handBrakeTorqueMax);
       }
-      if (
-        oldBehaviorData.hasBackWheelDrive !== newBehaviorData.hasBackWheelDrive
-      ) {
-        this.setBackWheelDrive(newBehaviorData.hasBackWheelDrive);
+      if (behaviorData.hasBackWheelDrive !== undefined) {
+        this.setBackWheelDrive(behaviorData.hasBackWheelDrive);
       }
-      if (
-        oldBehaviorData.hasFrontWheelDrive !==
-        newBehaviorData.hasFrontWheelDrive
-      ) {
-        this.setFrontWheelDrive(newBehaviorData.hasFrontWheelDrive);
+      if (behaviorData.hasFrontWheelDrive !== undefined) {
+        this.setFrontWheelDrive(behaviorData.hasFrontWheelDrive);
       }
-      if (
-        oldBehaviorData.pitchRollAngleMax !== newBehaviorData.pitchRollAngleMax
-      ) {
-        this.setPitchRollAngleMax(newBehaviorData.pitchRollAngleMax);
+      if (behaviorData.pitchRollAngleMax !== undefined) {
+        this.setPitchRollAngleMax(behaviorData.pitchRollAngleMax);
       }
       return true;
     }
diff --git a/Extensions/Physics3DBehavior/PhysicsCharacter3DRuntimeBehavior.ts b/Extensions/Physics3DBehavior/PhysicsCharacter3DRuntimeBehavior.ts
index 451e4d2a2..5e983170a 100644
--- a/Extensions/Physics3DBehavior/PhysicsCharacter3DRuntimeBehavior.ts
+++ b/Extensions/Physics3DBehavior/PhysicsCharacter3DRuntimeBehavior.ts
@@ -263,61 +263,44 @@ namespace gdjs {
       return this._physics3D;
     }
 
-    override updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
-      if (oldBehaviorData.gravity !== newBehaviorData.gravity) {
-        this.setGravity(newBehaviorData.gravity);
+    override applyBehaviorOverriding(behaviorData): boolean {
+      if (behaviorData.gravity !== undefined) {
+        this.setGravity(behaviorData.gravity);
       }
-      if (oldBehaviorData.maxFallingSpeed !== newBehaviorData.maxFallingSpeed) {
-        this.setMaxFallingSpeed(newBehaviorData.maxFallingSpeed);
+      if (behaviorData.maxFallingSpeed !== undefined) {
+        this.setMaxFallingSpeed(behaviorData.maxFallingSpeed);
       }
-      if (
-        oldBehaviorData.forwardAcceleration !==
-        newBehaviorData.forwardAcceleration
-      ) {
-        this.setForwardAcceleration(newBehaviorData.forwardAcceleration);
+      if (behaviorData.forwardAcceleration !== undefined) {
+        this.setForwardAcceleration(behaviorData.forwardAcceleration);
       }
-      if (
-        oldBehaviorData.forwardDeceleration !==
-        newBehaviorData.forwardDeceleration
-      ) {
-        this.setForwardDeceleration(newBehaviorData.forwardDeceleration);
+      if (behaviorData.forwardDeceleration !== undefined) {
+        this.setForwardDeceleration(behaviorData.forwardDeceleration);
       }
-      if (oldBehaviorData.forwardSpeedMax !== newBehaviorData.forwardSpeedMax) {
-        this.setForwardSpeedMax(newBehaviorData.forwardSpeedMax);
+      if (behaviorData.forwardSpeedMax !== undefined) {
+        this.setForwardSpeedMax(behaviorData.forwardSpeedMax);
       }
-      if (
-        oldBehaviorData.sidewaysAcceleration !==
-        newBehaviorData.sidewaysAcceleration
-      ) {
-        this.setSidewaysAcceleration(newBehaviorData.sidewaysAcceleration);
+      if (behaviorData.sidewaysAcceleration !== undefined) {
+        this.setSidewaysAcceleration(behaviorData.sidewaysAcceleration);
       }
-      if (
-        oldBehaviorData.sidewaysDeceleration !==
-        newBehaviorData.sidewaysDeceleration
-      ) {
-        this.setSidewaysDeceleration(newBehaviorData.sidewaysDeceleration);
+      if (behaviorData.sidewaysDeceleration !== undefined) {
+        this.setSidewaysDeceleration(behaviorData.sidewaysDeceleration);
       }
-      if (
-        oldBehaviorData.sidewaysSpeedMax !== newBehaviorData.sidewaysSpeedMax
-      ) {
-        this.setSidewaysSpeedMax(newBehaviorData.sidewaysSpeedMax);
+      if (behaviorData.sidewaysSpeedMax !== undefined) {
+        this.setSidewaysSpeedMax(behaviorData.sidewaysSpeedMax);
       }
-      if (oldBehaviorData.jumpSustainTime !== newBehaviorData.jumpSustainTime) {
-        this.setJumpSustainTime(newBehaviorData.jumpSustainTime);
+      if (behaviorData.jumpSustainTime !== undefined) {
+        this.setJumpSustainTime(behaviorData.jumpSustainTime);
       }
-      if (oldBehaviorData.jumpHeight !== newBehaviorData.jumpHeight) {
-        this.setJumpSpeed(this.getJumpSpeedToReach(newBehaviorData.jumpHeight));
+      if (behaviorData.jumpHeight !== undefined) {
+        this.setJumpSpeed(this.getJumpSpeedToReach(behaviorData.jumpHeight));
       }
-      if (
-        oldBehaviorData.shouldBindObjectAndForwardAngle !==
-        newBehaviorData.shouldBindObjectAndForwardAngle
-      ) {
+      if (behaviorData.shouldBindObjectAndForwardAngle !== undefined) {
         this.setShouldBindObjectAndForwardAngle(
-          newBehaviorData.shouldBindObjectAndForwardAngle
+          behaviorData.shouldBindObjectAndForwardAngle
         );
       }
-      if (oldBehaviorData.stairHeightMax !== newBehaviorData.stairHeightMax) {
-        this.setStairHeightMax(newBehaviorData.stairHeightMax);
+      if (behaviorData.stairHeightMax !== undefined) {
+        this.setStairHeightMax(behaviorData.stairHeightMax);
       }
       return true;
     }
diff --git a/Extensions/PhysicsBehavior/physicsruntimebehavior.ts b/Extensions/PhysicsBehavior/physicsruntimebehavior.ts
index e1abc9e22..9e6a48693 100644
--- a/Extensions/PhysicsBehavior/physicsruntimebehavior.ts
+++ b/Extensions/PhysicsBehavior/physicsruntimebehavior.ts
@@ -181,29 +181,29 @@ namespace gdjs {
     }
 
     //See b2Vec2 method
-    updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
-      if (oldBehaviorData.dynamic !== newBehaviorData.dynamic) {
-        if (newBehaviorData.dynamic) {
+    override applyBehaviorOverriding(behaviorData): boolean {
+      if (behaviorData.dynamic !== undefined) {
+        if (behaviorData.dynamic) {
           this.setDynamic();
         } else {
           this.setStatic();
         }
       }
-      if (oldBehaviorData.angularDamping !== newBehaviorData.angularDamping) {
-        this.setAngularDamping(newBehaviorData.angularDamping);
+      if (behaviorData.angularDamping !== undefined) {
+        this.setAngularDamping(behaviorData.angularDamping);
       }
-      if (oldBehaviorData.linearDamping !== newBehaviorData.linearDamping) {
-        this.setLinearDamping(newBehaviorData.linearDamping);
+      if (behaviorData.linearDamping !== undefined) {
+        this.setLinearDamping(behaviorData.linearDamping);
       }
-      if (oldBehaviorData.isBullet !== newBehaviorData.isBullet) {
-        if (newBehaviorData.isBullet) {
+      if (behaviorData.isBullet !== undefined) {
+        if (behaviorData.isBullet) {
           this.setAsBullet();
         } else {
           this.dontSetAsBullet();
         }
       }
-      if (oldBehaviorData.fixedRotation !== newBehaviorData.fixedRotation) {
-        if (newBehaviorData.fixedRotation) {
+      if (behaviorData.fixedRotation !== undefined) {
+        if (behaviorData.fixedRotation) {
           this.setFixedRotation();
         } else {
           this.setFreeRotation();
@@ -211,19 +211,16 @@ namespace gdjs {
       }
 
       // TODO: make these properties updatable.
-      if (oldBehaviorData.massDensity !== newBehaviorData.massDensity) {
+      if (behaviorData.massDensity !== undefined) {
         return false;
       }
-      if (oldBehaviorData.averageFriction !== newBehaviorData.averageFriction) {
+      if (behaviorData.averageFriction !== undefined) {
         return false;
       }
-      if (
-        oldBehaviorData.averageRestitution !==
-        newBehaviorData.averageRestitution
-      ) {
+      if (behaviorData.averageRestitution !== undefined) {
         return false;
       }
-      if (oldBehaviorData.shapeType !== newBehaviorData.shapeType) {
+      if (behaviorData.shapeType !== undefined) {
         return false;
       }
       return true;
diff --git a/Extensions/PlatformBehavior/platformerobjectruntimebehavior.ts b/Extensions/PlatformBehavior/platformerobjectruntimebehavior.ts
index a57e02138..22803a67e 100644
--- a/Extensions/PlatformBehavior/platformerobjectruntimebehavior.ts
+++ b/Extensions/PlatformBehavior/platformerobjectruntimebehavior.ts
@@ -368,56 +368,45 @@ namespace gdjs {
       this._ignoreDefaultControlsAsSyncedByNetwork = !options.keepControl;
     }
 
-    updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
-      if (oldBehaviorData.gravity !== newBehaviorData.gravity) {
-        this.setGravity(newBehaviorData.gravity);
+    override applyBehaviorOverriding(behaviorData): boolean {
+      if (behaviorData.gravity !== undefined) {
+        this.setGravity(behaviorData.gravity);
       }
-      if (oldBehaviorData.maxFallingSpeed !== newBehaviorData.maxFallingSpeed) {
-        this.setMaxFallingSpeed(newBehaviorData.maxFallingSpeed);
+      if (behaviorData.maxFallingSpeed !== undefined) {
+        this.setMaxFallingSpeed(behaviorData.maxFallingSpeed);
       }
-      if (oldBehaviorData.acceleration !== newBehaviorData.acceleration) {
-        this.setAcceleration(newBehaviorData.acceleration);
+      if (behaviorData.acceleration !== undefined) {
+        this.setAcceleration(behaviorData.acceleration);
       }
-      if (oldBehaviorData.deceleration !== newBehaviorData.deceleration) {
-        this.setDeceleration(newBehaviorData.deceleration);
+      if (behaviorData.deceleration !== undefined) {
+        this.setDeceleration(behaviorData.deceleration);
       }
-      if (oldBehaviorData.maxSpeed !== newBehaviorData.maxSpeed) {
-        this.setMaxSpeed(newBehaviorData.maxSpeed);
+      if (behaviorData.maxSpeed !== undefined) {
+        this.setMaxSpeed(behaviorData.maxSpeed);
       }
-      if (oldBehaviorData.jumpSpeed !== newBehaviorData.jumpSpeed) {
-        this.setJumpSpeed(newBehaviorData.jumpSpeed);
+      if (behaviorData.jumpSpeed !== undefined) {
+        this.setJumpSpeed(behaviorData.jumpSpeed);
       }
-      if (
-        oldBehaviorData.canGrabPlatforms !== newBehaviorData.canGrabPlatforms
-      ) {
-        this.setCanGrabPlatforms(newBehaviorData.canGrabPlatforms);
+      if (behaviorData.canGrabPlatforms !== undefined) {
+        this.setCanGrabPlatforms(behaviorData.canGrabPlatforms);
       }
-      if (
-        oldBehaviorData.canGrabWithoutMoving !==
-        newBehaviorData.canGrabWithoutMoving
-      ) {
-        this._canGrabWithoutMoving = newBehaviorData.canGrabWithoutMoving;
+      if (behaviorData.canGrabWithoutMoving !== undefined) {
+        this._canGrabWithoutMoving = behaviorData.canGrabWithoutMoving;
       }
-      if (oldBehaviorData.yGrabOffset !== newBehaviorData.yGrabOffset) {
-        this._yGrabOffset = newBehaviorData.yGrabOffset;
+      if (behaviorData.yGrabOffset !== undefined) {
+        this._yGrabOffset = behaviorData.yGrabOffset;
       }
-      if (oldBehaviorData.xGrabTolerance !== newBehaviorData.xGrabTolerance) {
-        this._xGrabTolerance = newBehaviorData.xGrabTolerance;
+      if (behaviorData.xGrabTolerance !== undefined) {
+        this._xGrabTolerance = behaviorData.xGrabTolerance;
       }
-      if (oldBehaviorData.jumpSustainTime !== newBehaviorData.jumpSustainTime) {
-        this.setJumpSustainTime(newBehaviorData.jumpSustainTime);
+      if (behaviorData.jumpSustainTime !== undefined) {
+        this.setJumpSustainTime(behaviorData.jumpSustainTime);
       }
-      if (
-        oldBehaviorData.useLegacyTrajectory !==
-        newBehaviorData.useLegacyTrajectory
-      ) {
-        this._useLegacyTrajectory = newBehaviorData.useLegacyTrajectory;
+      if (behaviorData.useLegacyTrajectory !== undefined) {
+        this._useLegacyTrajectory = behaviorData.useLegacyTrajectory;
       }
-      if (
-        oldBehaviorData.canGoDownFromJumpthru !==
-        newBehaviorData.canGoDownFromJumpthru
-      ) {
-        this._canGoDownFromJumpthru = newBehaviorData.canGoDownFromJumpthru;
+      if (behaviorData.canGoDownFromJumpthru !== undefined) {
+        this._canGoDownFromJumpthru = behaviorData.canGoDownFromJumpthru;
       }
       return true;
     }
diff --git a/Extensions/PlatformBehavior/platformruntimebehavior.ts b/Extensions/PlatformBehavior/platformruntimebehavior.ts
index 78be79d30..c66e418b7 100644
--- a/Extensions/PlatformBehavior/platformruntimebehavior.ts
+++ b/Extensions/PlatformBehavior/platformruntimebehavior.ts
@@ -146,15 +146,15 @@ namespace gdjs {
       this._manager = PlatformObjectsManager.getManager(instanceContainer);
     }
 
-    updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
-      if (oldBehaviorData.platformType !== newBehaviorData.platformType) {
-        this.changePlatformType(newBehaviorData.platformType);
+    override applyBehaviorOverriding(behaviorData): boolean {
+      if (behaviorData.platformType !== undefined) {
+        this.changePlatformType(behaviorData.platformType);
       }
-      if (oldBehaviorData.canBeGrabbed !== newBehaviorData.canBeGrabbed) {
-        this._canBeGrabbed = newBehaviorData.canBeGrabbed;
+      if (behaviorData.canBeGrabbed !== undefined) {
+        this._canBeGrabbed = behaviorData.canBeGrabbed;
       }
-      if (oldBehaviorData.yGrabOffset !== newBehaviorData.yGrabOffset) {
-        this._yGrabOffset = newBehaviorData.yGrabOffset;
+      if (behaviorData.yGrabOffset !== undefined) {
+        this._yGrabOffset = behaviorData.yGrabOffset;
       }
       return true;
     }
diff --git a/Extensions/PrimitiveDrawing/shapepainterruntimeobject.ts b/Extensions/PrimitiveDrawing/shapepainterruntimeobject.ts
index 4251053b0..87946410b 100644
--- a/Extensions/PrimitiveDrawing/shapepainterruntimeobject.ts
+++ b/Extensions/PrimitiveDrawing/shapepainterruntimeobject.ts
@@ -100,9 +100,10 @@ namespace gdjs {
      */
     constructor(
       instanceContainer: gdjs.RuntimeInstanceContainer,
-      shapePainterObjectData: ShapePainterObjectData
+      shapePainterObjectData: ShapePainterObjectData,
+      instanceData?: InstanceData
     ) {
-      super(instanceContainer, shapePainterObjectData);
+      super(instanceContainer, shapePainterObjectData, instanceData);
       this._fillColor =
         typeof shapePainterObjectData.fillColor === 'string'
           ? gdjs.rgbOrHexStringToNumber(shapePainterObjectData.fillColor)
diff --git a/Extensions/Spine/spineruntimeobject.ts b/Extensions/Spine/spineruntimeobject.ts
index 28a91f1f6..d1877a793 100644
--- a/Extensions/Spine/spineruntimeobject.ts
+++ b/Extensions/Spine/spineruntimeobject.ts
@@ -68,9 +68,10 @@ namespace gdjs {
      */
     constructor(
       instanceContainer: gdjs.RuntimeInstanceContainer,
-      objectData: SpineObjectData
+      objectData: SpineObjectData,
+      instanceData?: InstanceData
     ) {
-      super(instanceContainer, objectData);
+      super(instanceContainer, objectData, instanceData);
 
       this._animations = objectData.content.animations;
       this._originalScale = objectData.content.scale;
diff --git a/Extensions/TextEntryObject/textentryruntimeobject.ts b/Extensions/TextEntryObject/textentryruntimeobject.ts
index 3ff0f8184..441f7e13c 100644
--- a/Extensions/TextEntryObject/textentryruntimeobject.ts
+++ b/Extensions/TextEntryObject/textentryruntimeobject.ts
@@ -19,9 +19,10 @@ namespace gdjs {
      */
     constructor(
       instanceContainer: gdjs.RuntimeInstanceContainer,
-      textEntryObjectData: ObjectData
+      textEntryObjectData: ObjectData,
+      instanceData?: InstanceData
     ) {
-      super(instanceContainer, textEntryObjectData);
+      super(instanceContainer, textEntryObjectData, instanceData);
       this._renderer = new gdjs.TextEntryRuntimeObjectRenderer(this);
 
       // *ALWAYS* call `this.onCreated()` at the very end of your object constructor.
diff --git a/Extensions/TextInput/textinputruntimeobject.ts b/Extensions/TextInput/textinputruntimeobject.ts
index e4cfd3056..80be7646f 100644
--- a/Extensions/TextInput/textinputruntimeobject.ts
+++ b/Extensions/TextInput/textinputruntimeobject.ts
@@ -134,9 +134,10 @@ namespace gdjs {
 
     constructor(
       instanceContainer: gdjs.RuntimeInstanceContainer,
-      objectData: TextInputObjectData
+      objectData: TextInputObjectData,
+      instanceData?: InstanceData
     ) {
-      super(instanceContainer, objectData);
+      super(instanceContainer, objectData, instanceData);
 
       this._string = objectData.content.initialValue;
       this._placeholder = objectData.content.placeholder;
diff --git a/Extensions/TextObject/textruntimeobject.ts b/Extensions/TextObject/textruntimeobject.ts
index 92bdb0816..339c35938 100644
--- a/Extensions/TextObject/textruntimeobject.ts
+++ b/Extensions/TextObject/textruntimeobject.ts
@@ -134,9 +134,10 @@ namespace gdjs {
      */
     constructor(
       instanceContainer: gdjs.RuntimeInstanceContainer,
-      textObjectData: TextObjectData
+      textObjectData: TextObjectData,
+      instanceData?: InstanceData
     ) {
-      super(instanceContainer, textObjectData);
+      super(instanceContainer, textObjectData, instanceData);
       const content = textObjectData.content;
       this._characterSize = Math.max(1, content.characterSize);
       this._fontName = content.font;
diff --git a/Extensions/TileMap/simpletilemapruntimeobject.ts b/Extensions/TileMap/simpletilemapruntimeobject.ts
index 49a50ac17..65fc206d4 100644
--- a/Extensions/TileMap/simpletilemapruntimeobject.ts
+++ b/Extensions/TileMap/simpletilemapruntimeobject.ts
@@ -71,9 +71,10 @@ namespace gdjs {
 
     constructor(
       instanceContainer: gdjs.RuntimeInstanceContainer,
-      objectData: ObjectData & SimpleTileMapObjectDataType
+      objectData: ObjectData & SimpleTileMapObjectDataType,
+      instanceData?: InstanceData
     ) {
-      super(instanceContainer, objectData);
+      super(instanceContainer, objectData, instanceData);
       this._atlasImage = objectData.content.atlasImage;
       this._rowCount = objectData.content.rowCount;
       this._columnCount = objectData.content.columnCount;
diff --git a/Extensions/TileMap/tilemapcollisionmaskruntimeobject.ts b/Extensions/TileMap/tilemapcollisionmaskruntimeobject.ts
index 4e8d821a7..519204c30 100644
--- a/Extensions/TileMap/tilemapcollisionmaskruntimeobject.ts
+++ b/Extensions/TileMap/tilemapcollisionmaskruntimeobject.ts
@@ -88,8 +88,12 @@ namespace gdjs {
      */
     private _transformationIsUpToDate: boolean = false;
 
-    constructor(instanceContainer: gdjs.RuntimeInstanceContainer, objectData) {
-      super(instanceContainer, objectData);
+    constructor(
+      instanceContainer: gdjs.RuntimeInstanceContainer,
+      objectData,
+      instanceData?: InstanceData
+    ) {
+      super(instanceContainer, objectData, instanceData);
       this._tilemapJsonFile = objectData.content.tilemapJsonFile;
       this._tilesetJsonFile = objectData.content.tilesetJsonFile;
       this._collisionMaskTag = objectData.content.collisionMaskTag;
diff --git a/Extensions/TileMap/tilemapruntimeobject.ts b/Extensions/TileMap/tilemapruntimeobject.ts
index a6e964a46..104c8c0cc 100644
--- a/Extensions/TileMap/tilemapruntimeobject.ts
+++ b/Extensions/TileMap/tilemapruntimeobject.ts
@@ -65,9 +65,10 @@ namespace gdjs {
 
     constructor(
       instanceContainer: gdjs.RuntimeInstanceContainer,
-      objectData: TilemapObjectData
+      objectData: TilemapObjectData,
+      instanceData?: InstanceData
     ) {
-      super(instanceContainer, objectData);
+      super(instanceContainer, objectData, instanceData);
       this._tilemapJsonFile = objectData.content.tilemapJsonFile;
       this._tilesetJsonFile = objectData.content.tilesetJsonFile;
       this._tilemapAtlasImage = objectData.content.tilemapAtlasImage;
diff --git a/Extensions/TiledSpriteObject/tiledspriteruntimeobject.ts b/Extensions/TiledSpriteObject/tiledspriteruntimeobject.ts
index 6aa22b592..7925b0c84 100644
--- a/Extensions/TiledSpriteObject/tiledspriteruntimeobject.ts
+++ b/Extensions/TiledSpriteObject/tiledspriteruntimeobject.ts
@@ -63,9 +63,10 @@ namespace gdjs {
      */
     constructor(
       instanceContainer: gdjs.RuntimeInstanceContainer,
-      tiledSpriteObjectData: TiledSpriteObjectData
+      tiledSpriteObjectData: TiledSpriteObjectData,
+      instanceData?: InstanceData
     ) {
-      super(instanceContainer, tiledSpriteObjectData);
+      super(instanceContainer, tiledSpriteObjectData, instanceData);
       this._objectData = tiledSpriteObjectData;
       this._renderer = new gdjs.TiledSpriteRuntimeObjectRenderer(
         this,
diff --git a/Extensions/TopDownMovementBehavior/topdownmovementruntimebehavior.ts b/Extensions/TopDownMovementBehavior/topdownmovementruntimebehavior.ts
index deea3582b..305c9374c 100644
--- a/Extensions/TopDownMovementBehavior/topdownmovementruntimebehavior.ts
+++ b/Extensions/TopDownMovementBehavior/topdownmovementruntimebehavior.ts
@@ -184,49 +184,42 @@ namespace gdjs {
       this._ignoreDefaultControlsAsSyncedByNetwork = !options.keepControl;
     }
 
-    updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
-      if (oldBehaviorData.allowDiagonals !== newBehaviorData.allowDiagonals) {
-        this._allowDiagonals = newBehaviorData.allowDiagonals;
+    override applyBehaviorOverriding(behaviorData): boolean {
+      if (behaviorData.allowDiagonals !== undefined) {
+        this._allowDiagonals = behaviorData.allowDiagonals;
       }
-      if (oldBehaviorData.acceleration !== newBehaviorData.acceleration) {
-        this._acceleration = newBehaviorData.acceleration;
+      if (behaviorData.acceleration !== undefined) {
+        this._acceleration = behaviorData.acceleration;
       }
-      if (oldBehaviorData.deceleration !== newBehaviorData.deceleration) {
-        this._deceleration = newBehaviorData.deceleration;
+      if (behaviorData.deceleration !== undefined) {
+        this._deceleration = behaviorData.deceleration;
       }
-      if (oldBehaviorData.maxSpeed !== newBehaviorData.maxSpeed) {
-        this._maxSpeed = newBehaviorData.maxSpeed;
+      if (behaviorData.maxSpeed !== undefined) {
+        this._maxSpeed = behaviorData.maxSpeed;
       }
-      if (oldBehaviorData.angularMaxSpeed !== newBehaviorData.angularMaxSpeed) {
-        this._angularMaxSpeed = newBehaviorData.angularMaxSpeed;
+      if (behaviorData.angularMaxSpeed !== undefined) {
+        this._angularMaxSpeed = behaviorData.angularMaxSpeed;
       }
-      if (oldBehaviorData.rotateObject !== newBehaviorData.rotateObject) {
-        this._rotateObject = newBehaviorData.rotateObject;
+      if (behaviorData.rotateObject !== undefined) {
+        this._rotateObject = behaviorData.rotateObject;
       }
-      if (oldBehaviorData.angleOffset !== newBehaviorData.angleOffset) {
-        this._angleOffset = newBehaviorData.angleOffset;
+      if (behaviorData.angleOffset !== undefined) {
+        this._angleOffset = behaviorData.angleOffset;
+      }
+      if (behaviorData.ignoreDefaultControls !== undefined) {
+        this._ignoreDefaultControls = behaviorData.ignoreDefaultControls;
       }
       if (
-        oldBehaviorData.ignoreDefaultControls !==
-        newBehaviorData.ignoreDefaultControls
-      ) {
-        this._ignoreDefaultControls = newBehaviorData.ignoreDefaultControls;
-      }
-      if (
-        oldBehaviorData.platformType !== newBehaviorData.platformType ||
-        oldBehaviorData.customIsometryAngle !==
-          newBehaviorData.customIsometryAngle
+        behaviorData.platformType !== undefined ||
+        behaviorData.customIsometryAngle !== undefined
       ) {
         this.setViewpoint(
-          newBehaviorData.platformType,
-          newBehaviorData.customIsometryAngle
+          behaviorData.platformType,
+          behaviorData.customIsometryAngle
         );
       }
-      if (
-        oldBehaviorData.movementAngleOffset !==
-        newBehaviorData.movementAngleOffset
-      ) {
-        this._movementAngleOffset = newBehaviorData.movementAngleOffset;
+      if (behaviorData.movementAngleOffset !== undefined) {
+        this._movementAngleOffset = behaviorData.movementAngleOffset;
       }
       return true;
     }
diff --git a/Extensions/TweenBehavior/tweenruntimebehavior.ts b/Extensions/TweenBehavior/tweenruntimebehavior.ts
index b547a764e..c4f3c180e 100644
--- a/Extensions/TweenBehavior/tweenruntimebehavior.ts
+++ b/Extensions/TweenBehavior/tweenruntimebehavior.ts
@@ -390,10 +390,7 @@ namespace gdjs {
       super(instanceContainer, behaviorData, owner);
     }
 
-    updateFromBehaviorData(
-      oldBehaviorData: BehaviorData,
-      newBehaviorData: BehaviorData
-    ): boolean {
+    override applyBehaviorOverriding(behaviorData: BehaviorData): boolean {
       // Nothing to update.
       return true;
     }
diff --git a/Extensions/Video/videoruntimeobject.ts b/Extensions/Video/videoruntimeobject.ts
index be9b7d081..852e63d2b 100644
--- a/Extensions/Video/videoruntimeobject.ts
+++ b/Extensions/Video/videoruntimeobject.ts
@@ -70,9 +70,10 @@ namespace gdjs {
      */
     constructor(
       instanceContainer: gdjs.RuntimeInstanceContainer,
-      videoObjectData: VideoObjectData
+      videoObjectData: VideoObjectData,
+      instanceData?: InstanceData
     ) {
-      super(instanceContainer, videoObjectData);
+      super(instanceContainer, videoObjectData, instanceData);
       this._opacity = videoObjectData.content.opacity;
       this._loop = videoObjectData.content.loop;
       this._volume = videoObjectData.content.volume;
diff --git a/GDJS/GDJS/Events/CodeGeneration/BehaviorCodeGenerator.cpp b/GDJS/GDJS/Events/CodeGeneration/BehaviorCodeGenerator.cpp
index 669722e96..67ae28f5b 100644
--- a/GDJS/GDJS/Events/CodeGeneration/BehaviorCodeGenerator.cpp
+++ b/GDJS/GDJS/Events/CodeGeneration/BehaviorCodeGenerator.cpp
@@ -207,7 +207,7 @@ CODE_NAMESPACE.RUNTIME_BEHAVIOR_CLASSNAME = class RUNTIME_BEHAVIOR_CLASSNAME ext
   }
 
   // Hot-reload:
-  updateFromBehaviorData(oldBehaviorData, newBehaviorData) {
+  applyBehaviorOverriding(behaviorOverriding) {
     UPDATE_FROM_BEHAVIOR_DATA_CODE
 
     return true;
@@ -396,8 +396,8 @@ gd::String BehaviorCodeGenerator::GenerateUpdatePropertyFromBehaviorDataCode(
     const gd::EventsBasedBehavior& eventsBasedBehavior,
     const gd::NamedPropertyDescriptor& property) {
   return gd::String(R"jscode_template(
-    if (oldBehaviorData.PROPERTY_NAME !== newBehaviorData.PROPERTY_NAME)
-      this._behaviorData.PROPERTY_NAME = newBehaviorData.PROPERTY_NAME;)jscode_template")
+    if (behaviorOverriding.PROPERTY_NAME !== undefined)
+      this._behaviorData.PROPERTY_NAME = behaviorOverriding.PROPERTY_NAME;)jscode_template")
       .FindAndReplace("PROPERTY_NAME", property.GetName());
 }
 
diff --git a/GDJS/GDJS/Events/CodeGeneration/ObjectCodeGenerator.cpp b/GDJS/GDJS/Events/CodeGeneration/ObjectCodeGenerator.cpp
index 4913690d6..109c78fc7 100644
--- a/GDJS/GDJS/Events/CodeGeneration/ObjectCodeGenerator.cpp
+++ b/GDJS/GDJS/Events/CodeGeneration/ObjectCodeGenerator.cpp
@@ -204,8 +204,8 @@ CODE_NAMESPACE = CODE_NAMESPACE || {};
  * Object generated from OBJECT_FULL_NAME
  */
 CODE_NAMESPACE.RUNTIME_OBJECT_CLASSNAME = class RUNTIME_OBJECT_CLASSNAME extends RUNTIME_OBJECT_BASE_CLASS_NAME {
-  constructor(parentInstanceContainer, objectData) {
-    super(parentInstanceContainer, objectData);
+  constructor(parentInstanceContainer, objectData, instanceData) {
+    super(parentInstanceContainer, objectData, instanceData);
     this._parentInstanceContainer = parentInstanceContainer;
 
     this._onceTriggers = new gdjs.OnceTriggers();
diff --git a/GDJS/Runtime/CustomRuntimeObject.ts b/GDJS/Runtime/CustomRuntimeObject.ts
index 802194d55..12079d94d 100644
--- a/GDJS/Runtime/CustomRuntimeObject.ts
+++ b/GDJS/Runtime/CustomRuntimeObject.ts
@@ -103,9 +103,10 @@ namespace gdjs {
      */
     constructor(
       parent: gdjs.RuntimeInstanceContainer,
-      objectData: ObjectData & CustomObjectConfiguration
+      objectData: ObjectData & CustomObjectConfiguration,
+      instanceData: InstanceData | undefined
     ) {
-      super(parent, objectData);
+      super(parent, objectData, instanceData);
       this._type = objectData.type;
       this._instanceContainer = new gdjs.CustomRuntimeObjectInstanceContainer(
         parent,
diff --git a/GDJS/Runtime/CustomRuntimeObject2D.ts b/GDJS/Runtime/CustomRuntimeObject2D.ts
index 8ed804c38..2ad087250 100644
--- a/GDJS/Runtime/CustomRuntimeObject2D.ts
+++ b/GDJS/Runtime/CustomRuntimeObject2D.ts
@@ -6,9 +6,10 @@ namespace gdjs {
   export class CustomRuntimeObject2D extends gdjs.CustomRuntimeObject {
     constructor(
       parent: gdjs.RuntimeInstanceContainer,
-      objectData: ObjectData & CustomObjectConfiguration
+      objectData: ObjectData & CustomObjectConfiguration,
+      instanceData?: InstanceData
     ) {
-      super(parent, objectData);
+      super(parent, objectData, instanceData);
     }
 
     protected override _createRender(): gdjs.CustomRuntimeObject2DRenderer {
diff --git a/GDJS/Runtime/CustomRuntimeObjectInstanceContainer.ts b/GDJS/Runtime/CustomRuntimeObjectInstanceContainer.ts
index d56670ebc..5860ce866 100644
--- a/GDJS/Runtime/CustomRuntimeObjectInstanceContainer.ts
+++ b/GDJS/Runtime/CustomRuntimeObjectInstanceContainer.ts
@@ -70,8 +70,11 @@ namespace gdjs {
       this._orderedLayers.length = 0;
     }
 
-    createObject(objectName: string): gdjs.RuntimeObject | null {
-      const result = super.createObject(objectName);
+    override createObject(
+      objectName: string,
+      instanceData?: InstanceData
+    ): gdjs.RuntimeObject | null {
+      const result = super.createObject(objectName, instanceData);
       this._customObject.onChildrenLocationChanged();
       return result;
     }
diff --git a/GDJS/Runtime/InGameEditor/InGameEditor.tsx b/GDJS/Runtime/InGameEditor/InGameEditor.tsx
index 0dadecfc2..ebfecdaab 100644
--- a/GDJS/Runtime/InGameEditor/InGameEditor.tsx
+++ b/GDJS/Runtime/InGameEditor/InGameEditor.tsx
@@ -5071,9 +5071,10 @@ namespace gdjs {
 
     constructor(
       instanceContainer: gdjs.RuntimeInstanceContainer,
-      objectData: gdjs.Object3DData
+      objectData: gdjs.Object3DData,
+      instanceData?: InstanceData
     ) {
-      super(instanceContainer, objectData);
+      super(instanceContainer, objectData, instanceData);
       this._renderer = new UnknownRuntimeObjectRenderer(
         this,
         instanceContainer
diff --git a/GDJS/Runtime/RuntimeInstanceContainer.ts b/GDJS/Runtime/RuntimeInstanceContainer.ts
index 00c21f6fd..5a70e9cd2 100644
--- a/GDJS/Runtime/RuntimeInstanceContainer.ts
+++ b/GDJS/Runtime/RuntimeInstanceContainer.ts
@@ -357,7 +357,7 @@ namespace gdjs {
           continue;
         }
 
-        const newObject = this.createObject(objectName);
+        const newObject = this.createObject(objectName, instanceData);
         if (newObject !== null) {
           if (shouldTrackByPersistentUuid) {
             // Give the object the same persistentUuid as the instance, so that
@@ -660,7 +660,10 @@ namespace gdjs {
      * @param objectName The name of the object to be created
      * @return The created object
      */
-    createObject(objectName: string): gdjs.RuntimeObject | null {
+    createObject(
+      objectName: string,
+      instanceData?: InstanceData
+    ): gdjs.RuntimeObject | null {
       if (
         !this._objectsCtor.containsKey(objectName) ||
         !this._objects.containsKey(objectName)
@@ -685,7 +688,7 @@ namespace gdjs {
       const ctor = this._objectsCtor.get(objectName);
       let obj;
       if (!cache || cache.length === 0) {
-        obj = new ctor(this, objectData);
+        obj = new ctor(this, objectData, instanceData);
       } else {
         // Reuse an objet destroyed before. If there is an object in the cache,
         // then it means it does support reinitialization.
diff --git a/GDJS/Runtime/object-capabilities/AnimatableBehavior.ts b/GDJS/Runtime/object-capabilities/AnimatableBehavior.ts
index 0e8be66d9..6a24c2c2a 100644
--- a/GDJS/Runtime/object-capabilities/AnimatableBehavior.ts
+++ b/GDJS/Runtime/object-capabilities/AnimatableBehavior.ts
@@ -91,7 +91,7 @@ namespace gdjs {
       return false;
     }
 
-    updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
+    override applyBehaviorOverriding(behaviorData): boolean {
       // Nothing to update.
       return true;
     }
diff --git a/GDJS/Runtime/object-capabilities/EffectBehavior.ts b/GDJS/Runtime/object-capabilities/EffectBehavior.ts
index 19fe288f0..c505c24b3 100644
--- a/GDJS/Runtime/object-capabilities/EffectBehavior.ts
+++ b/GDJS/Runtime/object-capabilities/EffectBehavior.ts
@@ -80,7 +80,7 @@ namespace gdjs {
       return false;
     }
 
-    updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
+    override applyBehaviorOverriding(behaviorData): boolean {
       // Nothing to update.
       return true;
     }
diff --git a/GDJS/Runtime/object-capabilities/FlippableBehavior.ts b/GDJS/Runtime/object-capabilities/FlippableBehavior.ts
index 61e43b87b..d16964e62 100644
--- a/GDJS/Runtime/object-capabilities/FlippableBehavior.ts
+++ b/GDJS/Runtime/object-capabilities/FlippableBehavior.ts
@@ -38,7 +38,7 @@ namespace gdjs {
       return false;
     }
 
-    updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
+    override applyBehaviorOverriding(behaviorData): boolean {
       // Nothing to update.
       return true;
     }
diff --git a/GDJS/Runtime/object-capabilities/OpacityBehavior.ts b/GDJS/Runtime/object-capabilities/OpacityBehavior.ts
index 742794e63..1f4b16201 100644
--- a/GDJS/Runtime/object-capabilities/OpacityBehavior.ts
+++ b/GDJS/Runtime/object-capabilities/OpacityBehavior.ts
@@ -42,7 +42,7 @@ namespace gdjs {
       return false;
     }
 
-    updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
+    override applyBehaviorOverriding(behaviorData): boolean {
       // Nothing to update.
       return true;
     }
diff --git a/GDJS/Runtime/object-capabilities/ResizableBehavior.ts b/GDJS/Runtime/object-capabilities/ResizableBehavior.ts
index be1e733a2..461a4fdd6 100644
--- a/GDJS/Runtime/object-capabilities/ResizableBehavior.ts
+++ b/GDJS/Runtime/object-capabilities/ResizableBehavior.ts
@@ -64,7 +64,7 @@ namespace gdjs {
       return false;
     }
 
-    updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
+    override applyBehaviorOverriding(behaviorData): boolean {
       // Nothing to update.
       return true;
     }
diff --git a/GDJS/Runtime/object-capabilities/ScalableBehavior.ts b/GDJS/Runtime/object-capabilities/ScalableBehavior.ts
index 1c98fb1f0..fbbd76588 100644
--- a/GDJS/Runtime/object-capabilities/ScalableBehavior.ts
+++ b/GDJS/Runtime/object-capabilities/ScalableBehavior.ts
@@ -74,7 +74,7 @@ namespace gdjs {
       return false;
     }
 
-    updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
+    override applyBehaviorOverriding(behaviorData): boolean {
       // Nothing to update.
       return true;
     }
diff --git a/GDJS/Runtime/object-capabilities/TextContainerBehavior.ts b/GDJS/Runtime/object-capabilities/TextContainerBehavior.ts
index 94700da71..33f0579ed 100644
--- a/GDJS/Runtime/object-capabilities/TextContainerBehavior.ts
+++ b/GDJS/Runtime/object-capabilities/TextContainerBehavior.ts
@@ -41,7 +41,7 @@ namespace gdjs {
       return false;
     }
 
-    updateFromBehaviorData(oldBehaviorData, newBehaviorData): boolean {
+    override applyBehaviorOverriding(behaviorData): boolean {
       // Nothing to update.
       return true;
     }
diff --git a/GDJS/Runtime/runtimebehavior.ts b/GDJS/Runtime/runtimebehavior.ts
index 787a6a0b4..09a2db2f5 100644
--- a/GDJS/Runtime/runtimebehavior.ts
+++ b/GDJS/Runtime/runtimebehavior.ts
@@ -79,6 +79,22 @@ namespace gdjs {
       oldBehaviorData: BehaviorData,
       newBehaviorData: BehaviorData
     ): boolean {
+      const diffBehaviorData = {
+        name: newBehaviorData.name,
+        type: newBehaviorData.type,
+      };
+      for (const key in diffBehaviorData) {
+        const oldValue = oldBehaviorData[key];
+        const newValue = newBehaviorData[key];
+        if (newValue !== oldValue) {
+          diffBehaviorData[key] = newValue;
+        }
+      }
+      // If not redefined, mark by default the hot-reload as failed.
+      return this.applyBehaviorOverriding(diffBehaviorData);
+    }
+
+    applyBehaviorOverriding(behaviorOverriding: BehaviorData): boolean {
       // If not redefined, mark by default the hot-reload as failed.
       return false;
     }
diff --git a/GDJS/Runtime/runtimeobject.ts b/GDJS/Runtime/runtimeobject.ts
index 601883d46..555988326 100644
--- a/GDJS/Runtime/runtimeobject.ts
+++ b/GDJS/Runtime/runtimeobject.ts
@@ -240,7 +240,8 @@ namespace gdjs {
      */
     constructor(
       instanceContainer: gdjs.RuntimeInstanceContainer,
-      objectData: ObjectData
+      objectData: ObjectData,
+      instanceData: InstanceData | undefined
     ) {
       this.name = objectData.name || '';
       this.type = objectData.type || '';
@@ -275,6 +276,15 @@ namespace gdjs {
         }
         this._behaviorsTable.put(autoData.name, behavior);
       }
+      if (instanceData && instanceData.behaviorOverridings) {
+        for (const behaviorOverriding of instanceData.behaviorOverridings) {
+          const behavior = this.getBehavior(behaviorOverriding.name);
+          if (!behavior) {
+            continue;
+          }
+          behavior.applyBehaviorOverriding(behaviorOverriding);
+        }
+      }
       this._timers = new Hashtable();
     }
 
diff --git a/GDJS/Runtime/spriteruntimeobject.ts b/GDJS/Runtime/spriteruntimeobject.ts
index d865aad2a..e5e5c0ce6 100644
--- a/GDJS/Runtime/spriteruntimeobject.ts
+++ b/GDJS/Runtime/spriteruntimeobject.ts
@@ -73,9 +73,10 @@ namespace gdjs {
      */
     constructor(
       instanceContainer: gdjs.RuntimeInstanceContainer,
-      spriteObjectData: ObjectData & SpriteObjectDataType
+      spriteObjectData: ObjectData & SpriteObjectDataType,
+      instanceData?: InstanceData
     ) {
-      super(instanceContainer, spriteObjectData);
+      super(instanceContainer, spriteObjectData, instanceData);
       this._updateIfNotVisible = !!spriteObjectData.updateIfNotVisible;
       this._preScale = spriteObjectData.preScale || 1;
       this._renderer = new gdjs.SpriteRuntimeObjectRenderer(
diff --git a/GDJS/Runtime/types/project-data.d.ts b/GDJS/Runtime/types/project-data.d.ts
index 6eb8238c8..8280b7f83 100644
--- a/GDJS/Runtime/types/project-data.d.ts
+++ b/GDJS/Runtime/types/project-data.d.ts
@@ -450,6 +450,7 @@ declare interface InstanceData extends InstancePersistentUuidData {
   numberProperties: InstanceNumberProperty[];
   stringProperties: InstanceStringProperty[];
   initialVariables: RootVariableData[];
+  behaviorOverridings?: Array<BehaviorData & any>;
 }
 
 declare interface InstanceNumberProperty {
diff --git a/GDJS/tests/tests-utils/init.pixiruntimegamewithassets.js b/GDJS/tests/tests-utils/init.pixiruntimegamewithassets.js
index 9d5b6a23a..b60c36c7a 100644
--- a/GDJS/tests/tests-utils/init.pixiruntimegamewithassets.js
+++ b/GDJS/tests/tests-utils/init.pixiruntimegamewithassets.js
@@ -4,14 +4,18 @@
  * Create and return a game with a few assets loaded, to be used in tests
  * needing real images.
  * @internal
+ * @param props {?{customObjectInstances?: Array<InstanceData>}}
  * @returns {Promise<gdjs.RuntimeGame>} A promise resolving with the game with loaded assets.
  */
-gdjs.getPixiRuntimeGameWithAssets = () => {
-  if (gdjs.getPixiRuntimeGameWithAssets._pixiRuntimeGameWithAssetsPromise) {
+gdjs.getPixiRuntimeGameWithAssets = (props = null) => {
+  if (
+    gdjs.getPixiRuntimeGameWithAssets._pixiRuntimeGameWithAssetsPromise &&
+    !props
+  ) {
     return gdjs.getPixiRuntimeGameWithAssets._pixiRuntimeGameWithAssetsPromise;
   }
 
-  var runtimeGame = new gdjs.RuntimeGame({
+  const runtimeGame = new gdjs.RuntimeGame({
     variables: [],
     properties: {
       adaptGameResolutionAtRuntime: true,
@@ -77,19 +81,19 @@ gdjs.getPixiRuntimeGameWithAssets = () => {
         title: '',
         variables: [],
         usedResources: [],
-      uiSettings: {
-        grid: false,
-        gridType: 'rectangular',
-        gridWidth: 10,
-        gridHeight: 10,
-        gridDepth: 10,
-        gridOffsetX: 0,
-        gridOffsetY: 0,
-        gridOffsetZ: 0,
-        gridColor: 0,
-        gridAlpha: 1,
-        snap: false,
-      }
+        uiSettings: {
+          grid: false,
+          gridType: 'rectangular',
+          gridWidth: 10,
+          gridHeight: 10,
+          gridDepth: 10,
+          gridOffsetX: 0,
+          gridOffsetY: 0,
+          gridOffsetZ: 0,
+          gridColor: 0,
+          gridAlpha: 1,
+          snap: false,
+        },
       },
     ],
     externalLayouts: [],
@@ -207,7 +211,7 @@ gdjs.getPixiRuntimeGameWithAssets = () => {
                 ],
               },
             ],
-            instances: [
+            instances: (props && props.customObjectInstances) || [
               {
                 angle: 0,
                 customSize: true,
@@ -242,20 +246,23 @@ gdjs.getPixiRuntimeGameWithAssets = () => {
     ],
   });
 
-  gdjs.getPixiRuntimeGameWithAssets._pixiRuntimeGameWithAssetsPromise =
-    new Promise((resolve) => {
-      runtimeGame.loadAllAssets(
-        () => {
-          console.info('Done loading assets for test game');
+  const pixiRuntimeGameWithAssetsPromise = new Promise((resolve) => {
+    runtimeGame.loadAllAssets(
+      () => {
+        console.info('Done loading assets for test game');
 
-          resolve(runtimeGame);
-        },
-        () => {
-          /* Ignore progress */
-        }
-      );
-    });
-  return gdjs.getPixiRuntimeGameWithAssets._pixiRuntimeGameWithAssetsPromise;
+        resolve(runtimeGame);
+      },
+      () => {
+        /* Ignore progress */
+      }
+    );
+  });
+  if (!props) {
+    gdjs.getPixiRuntimeGameWithAssets._pixiRuntimeGameWithAssetsPromise =
+      pixiRuntimeGameWithAssetsPromise;
+  }
+  return pixiRuntimeGameWithAssetsPromise;
 };
 
 /**
diff --git a/GDJS/tests/tests/CustomRuntimeObject.js b/GDJS/tests/tests/CustomRuntimeObject.js
index 59f85a5e1..ca5b730ad 100644
--- a/GDJS/tests/tests/CustomRuntimeObject.js
+++ b/GDJS/tests/tests/CustomRuntimeObject.js
@@ -61,7 +61,7 @@ describe('gdjs.CustomRuntimeObject', function () {
             },
           ],
         },
-      },
+      }
     });
     instanceContainer.addObject(customObject);
     return customObject;
diff --git a/GDevelop.js/Bindings/Bindings.idl b/GDevelop.js/Bindings/Bindings.idl
index 18df4cc34..fefb753b2 100644
--- a/GDevelop.js/Bindings/Bindings.idl
+++ b/GDevelop.js/Bindings/Bindings.idl
@@ -805,7 +805,9 @@ interface Behavior {
 
     [Value] MapStringPropertyDescriptor GetProperties();
     boolean UpdateProperty([Const] DOMString name, [Const] DOMString value);
+    void RemoveProperty([Const] DOMString name);
     void InitializeContent();
+    boolean HasPropertyValue([Const] DOMString name);
 
     void SerializeTo([Ref] SerializerElement element);
     void UnserializeFrom([Const, Ref] SerializerElement element);
@@ -1055,7 +1057,7 @@ interface ExternalLayout {
     [Ref] EditorSettings GetAssociatedEditorSettings();
 
     void SerializeTo([Ref] SerializerElement element);
-    void UnserializeFrom([Const, Ref] SerializerElement element);
+    void UnserializeFrom([Ref] Project project, [Const, Ref] SerializerElement element);
 };
 
 interface Effect {
@@ -1492,8 +1494,17 @@ interface InitialInstance {
 
     [Ref] VariablesContainer GetVariables();
 
+    boolean HasAnyOverriddenProperty([Const, Ref] gdObject obj);
+    boolean HasAnyOverriddenPropertyForBehavior([Const, Ref] Behavior behavior);
+    
+    boolean HasBehaviorOverridingNamed([Const] DOMString name);
+    Behavior AddNewBehaviorOverriding([Ref] Project project, [Const] DOMString type, [Const] DOMString name);
+    [Ref] Behavior GetBehaviorOverriding([Const] DOMString name);
+    void RemoveBehaviorOverriding([Const] DOMString name);
+    boolean RenameBehaviorOverriding([Const] DOMString oldName, [Const] DOMString name);
+
     void SerializeTo([Ref] SerializerElement element);
-    void UnserializeFrom([Const, Ref] SerializerElement element);
+    void UnserializeFrom([Ref] Project project, [Const, Ref] SerializerElement element);
 };
 
 interface InitialInstancesContainer {
@@ -1518,7 +1529,7 @@ interface InitialInstancesContainer {
     [Ref] InitialInstance InsertInitialInstance([Const, Ref] InitialInstance inst);
 
     void SerializeTo([Ref] SerializerElement element);
-    void UnserializeFrom([Const, Ref] SerializerElement element);
+    void UnserializeFrom([Ref] Project project, [Const, Ref] SerializerElement element);
 };
 
 interface HighestZOrderFinder {
diff --git a/GDevelop.js/__tests__/Core.js b/GDevelop.js/__tests__/Core.js
index 07ea513fe..0a70aea01 100644
--- a/GDevelop.js/__tests__/Core.js
+++ b/GDevelop.js/__tests__/Core.js
@@ -809,7 +809,7 @@ describe('libGD.js', function () {
       let initialInstance2 = layout
         .getInitialInstances()
         .insertNewInitialInstance();
-      initialInstance2.unserializeFrom(element);
+      initialInstance2.unserializeFrom(project, element);
       expect(initialInstance2.getObjectName()).toBe('MySpriteObject');
       expect(initialInstance2.getX()).toBe(150);
       expect(initialInstance2.getY()).toBe(140);
@@ -863,7 +863,7 @@ describe('libGD.js', function () {
       const migratedInstance = layout
         .getInitialInstances()
         .insertNewInitialInstance();
-      migratedInstance.unserializeFrom(element);
+      migratedInstance.unserializeFrom(project, element);
 
       element.delete();
       expect(migratedInstance.getX()).toBe(-100);
@@ -902,7 +902,7 @@ describe('libGD.js', function () {
       const instanceWithJustDepth = layout
         .getInitialInstances()
         .insertNewInitialInstance();
-      instanceWithJustDepth.unserializeFrom(element);
+      instanceWithJustDepth.unserializeFrom(project, element);
 
       element.delete();
       expect(instanceWithJustDepth.getX()).toBe(-100);
@@ -950,7 +950,7 @@ describe('libGD.js', function () {
       const initialInstance2 = layout
         .getInitialInstances()
         .insertNewInitialInstance();
-      initialInstance2.unserializeFrom(element);
+      initialInstance2.unserializeFrom(project, element);
       expect(initialInstance2.getX()).toBe(40);
       expect(initialInstance2.getY()).toBe(41);
       expect(initialInstance2.getZ()).toBe(42);
@@ -975,7 +975,7 @@ describe('libGD.js', function () {
 
       // The UUID must persist across serializations.
       const initialInstance2 = new gd.InitialInstance();
-      initialInstance2.unserializeFrom(element);
+      initialInstance2.unserializeFrom(project, element);
 
       let element2 = new gd.SerializerElement();
       initialInstance.serializeTo(element2);
diff --git a/GDevelop.js/types.d.ts b/GDevelop.js/types.d.ts
index 3be5da840..6feaa931a 100644
--- a/GDevelop.js/types.d.ts
+++ b/GDevelop.js/types.d.ts
@@ -692,7 +692,9 @@ export class Behavior extends EmscriptenObject {
   getTypeName(): string;
   getProperties(): MapStringPropertyDescriptor;
   updateProperty(name: string, value: string): boolean;
+  removeProperty(name: string): void;
   initializeContent(): void;
+  hasPropertyValue(name: string): boolean;
   serializeTo(element: SerializerElement): void;
   unserializeFrom(element: SerializerElement): void;
   isFolded(): boolean;
@@ -866,7 +868,7 @@ export class ExternalLayout extends EmscriptenObject {
   getInitialInstances(): InitialInstancesContainer;
   getAssociatedEditorSettings(): EditorSettings;
   serializeTo(element: SerializerElement): void;
-  unserializeFrom(element: SerializerElement): void;
+  unserializeFrom(project: Project, element: SerializerElement): void;
 }
 
 export class Effect extends EmscriptenObject {
@@ -1233,8 +1235,15 @@ export class InitialInstance extends EmscriptenObject {
   setRawDoubleProperty(name: string, value: number): void;
   setRawStringProperty(name: string, value: string): void;
   getVariables(): VariablesContainer;
+  hasAnyOverriddenProperty(obj: gdObject): boolean;
+  hasAnyOverriddenPropertyForBehavior(behavior: Behavior): boolean;
+  hasBehaviorOverridingNamed(name: string): boolean;
+  addNewBehaviorOverriding(project: Project, type: string, name: string): Behavior;
+  getBehaviorOverriding(name: string): Behavior;
+  removeBehaviorOverriding(name: string): void;
+  renameBehaviorOverriding(oldName: string, name: string): boolean;
   serializeTo(element: SerializerElement): void;
-  unserializeFrom(element: SerializerElement): void;
+  unserializeFrom(project: Project, element: SerializerElement): void;
 }
 
 export class InitialInstancesContainer extends EmscriptenObject {
@@ -1255,7 +1264,7 @@ export class InitialInstancesContainer extends EmscriptenObject {
   insertNewInitialInstance(): InitialInstance;
   insertInitialInstance(inst: InitialInstance): InitialInstance;
   serializeTo(element: SerializerElement): void;
-  unserializeFrom(element: SerializerElement): void;
+  unserializeFrom(project: Project, element: SerializerElement): void;
 }
 
 export class HighestZOrderFinder extends EmscriptenObject {
diff --git a/GDevelop.js/types/gdbehavior.js b/GDevelop.js/types/gdbehavior.js
index 083a1edc9..7a14a3b64 100644
--- a/GDevelop.js/types/gdbehavior.js
+++ b/GDevelop.js/types/gdbehavior.js
@@ -6,7 +6,9 @@ declare class gdBehavior {
   getTypeName(): string;
   getProperties(): gdMapStringPropertyDescriptor;
   updateProperty(name: string, value: string): boolean;
+  removeProperty(name: string): void;
   initializeContent(): void;
+  hasPropertyValue(name: string): boolean;
   serializeTo(element: gdSerializerElement): void;
   unserializeFrom(element: gdSerializerElement): void;
   isFolded(): boolean;
diff --git a/GDevelop.js/types/gdexternallayout.js b/GDevelop.js/types/gdexternallayout.js
index dde8d681a..551f9e133 100644
--- a/GDevelop.js/types/gdexternallayout.js
+++ b/GDevelop.js/types/gdexternallayout.js
@@ -8,7 +8,7 @@ declare class gdExternalLayout {
   getInitialInstances(): gdInitialInstancesContainer;
   getAssociatedEditorSettings(): gdEditorSettings;
   serializeTo(element: gdSerializerElement): void;
-  unserializeFrom(element: gdSerializerElement): void;
+  unserializeFrom(project: gdProject, element: gdSerializerElement): void;
   delete(): void;
   ptr: number;
 };
\ No newline at end of file
diff --git a/GDevelop.js/types/gdinitialinstance.js b/GDevelop.js/types/gdinitialinstance.js
index bfd726b91..9d2dd29d3 100644
--- a/GDevelop.js/types/gdinitialinstance.js
+++ b/GDevelop.js/types/gdinitialinstance.js
@@ -58,8 +58,15 @@ declare class gdInitialInstance {
   setRawDoubleProperty(name: string, value: number): void;
   setRawStringProperty(name: string, value: string): void;
   getVariables(): gdVariablesContainer;
+  hasAnyOverriddenProperty(obj: gdObject): boolean;
+  hasAnyOverriddenPropertyForBehavior(behavior: gdBehavior): boolean;
+  hasBehaviorOverridingNamed(name: string): boolean;
+  addNewBehaviorOverriding(project: gdProject, type: string, name: string): gdBehavior;
+  getBehaviorOverriding(name: string): gdBehavior;
+  removeBehaviorOverriding(name: string): void;
+  renameBehaviorOverriding(oldName: string, name: string): boolean;
   serializeTo(element: gdSerializerElement): void;
-  unserializeFrom(element: gdSerializerElement): void;
+  unserializeFrom(project: gdProject, element: gdSerializerElement): void;
   delete(): void;
   ptr: number;
 };
\ No newline at end of file
diff --git a/GDevelop.js/types/gdinitialinstancescontainer.js b/GDevelop.js/types/gdinitialinstancescontainer.js
index d866a26cc..a967c7fe7 100644
--- a/GDevelop.js/types/gdinitialinstancescontainer.js
+++ b/GDevelop.js/types/gdinitialinstancescontainer.js
@@ -17,7 +17,7 @@ declare class gdInitialInstancesContainer {
   insertNewInitialInstance(): gdInitialInstance;
   insertInitialInstance(inst: gdInitialInstance): gdInitialInstance;
   serializeTo(element: gdSerializerElement): void;
-  unserializeFrom(element: gdSerializerElement): void;
+  unserializeFrom(project: gdProject, element: gdSerializerElement): void;
   delete(): void;
   ptr: number;
 };
\ No newline at end of file
diff --git a/newIDE/app/src/BehaviorsEditor/Editors/BehaviorPropertiesEditor.js b/newIDE/app/src/BehaviorsEditor/Editors/BehaviorPropertiesEditor.js
index 6c19f045a..3ab99998a 100644
--- a/newIDE/app/src/BehaviorsEditor/Editors/BehaviorPropertiesEditor.js
+++ b/newIDE/app/src/BehaviorsEditor/Editors/BehaviorPropertiesEditor.js
@@ -29,7 +29,11 @@ const BehaviorPropertiesEditor = ({
       propertiesMapToSchema({
         properties: behavior.getProperties(),
         defaultValueProperties: behaviorMetadata.getProperties(),
-        getProperties: instance => instance.getProperties(),
+        getPropertyValue: (instance, name) =>
+          instance
+            .getProperties()
+            .get(name)
+            .getValue(),
         onUpdateProperty: (instance, name, value) => {
           instance.updateProperty(name, value);
         },
diff --git a/newIDE/app/src/BehaviorsEditor/index.js b/newIDE/app/src/BehaviorsEditor/index.js
index 844526832..3387ecb76 100644
--- a/newIDE/app/src/BehaviorsEditor/index.js
+++ b/newIDE/app/src/BehaviorsEditor/index.js
@@ -395,6 +395,7 @@ export const useManageObjectBehaviors = ({
       // Renaming a behavior is something that is really rare anyway! :)
 
       if (object.hasBehaviorNamed(newName)) return;
+      // TODO Add a refactor operation to update the behavior name in overridings of object instances
       object.renameBehavior(behavior.getName(), newName);
       onUpdate();
       if (onBehaviorsUpdated) onBehaviorsUpdated();
@@ -419,6 +420,7 @@ export const useManageObjectBehaviors = ({
       const answer = Window.showConfirmDialog(message);
 
       if (answer) {
+        // TODO Add a refactor operation to remove the behavior overridings in object instances
         object.removeBehavior(behaviorName);
         dependentBehaviors.forEach(name => object.removeBehavior(name));
         if (onSizeUpdated) onSizeUpdated();
diff --git a/newIDE/app/src/CompactPropertiesEditor/CompactPropertiesEditorByVisibility.js b/newIDE/app/src/CompactPropertiesEditor/CompactPropertiesEditorByVisibility.js
index 371c1faa9..ea89ca345 100644
--- a/newIDE/app/src/CompactPropertiesEditor/CompactPropertiesEditorByVisibility.js
+++ b/newIDE/app/src/CompactPropertiesEditor/CompactPropertiesEditorByVisibility.js
@@ -162,7 +162,7 @@ export const CompactPropertiesEditorByVisibility = ({
   instances: Instances,
   preventWrap?: boolean,
   removeSpacers?: boolean,
-  customizeBasicSchema?: Schema => Schema,
+  customizeBasicSchema?: (Schema => Schema) | null,
   placeholder: React.Node,
   onRefreshAllFields: () => void,
 
diff --git a/newIDE/app/src/CompactPropertiesEditor/CompactPropertiesEditorRowField.js b/newIDE/app/src/CompactPropertiesEditor/CompactPropertiesEditorRowField.js
index cf4a96970..2a99856c4 100644
--- a/newIDE/app/src/CompactPropertiesEditor/CompactPropertiesEditorRowField.js
+++ b/newIDE/app/src/CompactPropertiesEditor/CompactPropertiesEditorRowField.js
@@ -15,13 +15,13 @@ const styles = {
     textOverflow: 'ellipsis',
     lineHeight: '17px',
     maxHeight: 34, // 2 * lineHeight to limit to 2 lines.
-    opacity: 0.7,
   },
 };
 type Props = {|
   label: string,
   markdownDescription?: ?string,
   field: React.Node,
+  labelColor?: 'primary' | 'secondary',
 |};
 
 const CompactPropertiesEditorRowField = (props: Props) => {
@@ -52,7 +52,11 @@ const CompactPropertiesEditorRowField = (props: Props) => {
             },
           }}
         >
-          <Text noMargin style={styles.label}>
+          <Text
+            noMargin
+            style={styles.label}
+            color={props.labelColor === 'primary' ? 'primary' : 'secondary'}
+          >
             {props.label}
           </Text>
         </Tooltip>
diff --git a/newIDE/app/src/CompactPropertiesEditor/index.js b/newIDE/app/src/CompactPropertiesEditor/index.js
index 109b39f7b..dc309d70f 100644
--- a/newIDE/app/src/CompactPropertiesEditor/index.js
+++ b/newIDE/app/src/CompactPropertiesEditor/index.js
@@ -146,6 +146,23 @@ const getFieldEndAdornmentIcon = ({
   return null;
 };
 
+const isFieldHighlighted = ({
+  instances,
+  field,
+}: {|
+  instances: Instances,
+  field: ValueField,
+|}): any => {
+  if (!instances[0]) {
+    console.warn(
+      'isFieldHighlighted was called with an empty list of instances (or containing undefined). This is a bug that should be fixed.'
+    );
+    return false;
+  }
+
+  return field.isHighlighted ? field.isHighlighted(instances[0]) : false;
+};
+
 const getFieldLabel = ({
   instances,
   field,
@@ -247,6 +264,9 @@ const CompactPropertiesEditor = ({
             }}
             disabled={getDisabled({ instances, field })}
             fullWidth
+            labelColor={
+              isFieldHighlighted({ instances, field }) ? 'primary' : 'secondary'
+            }
           />
         );
       } else if (field.valueType === 'number') {
@@ -306,6 +326,11 @@ const CompactPropertiesEditor = ({
                   {...otherCommonProps}
                 />
               }
+              labelColor={
+                isFieldHighlighted({ instances, field })
+                  ? 'primary'
+                  : 'secondary'
+              }
             />
           );
         }
@@ -332,6 +357,9 @@ const CompactPropertiesEditor = ({
                 }}
               />
             }
+            labelColor={
+              isFieldHighlighted({ instances, field }) ? 'primary' : 'secondary'
+            }
           />
         );
       } else if (field.valueType === 'enumIcon') {
@@ -372,6 +400,9 @@ const CompactPropertiesEditor = ({
             value={getFieldValue({ instances, field })}
             label={getFieldLabel({ instances, field })}
             markdownDescription={getFieldDescription(field)}
+            labelColor={
+              isFieldHighlighted({ instances, field }) ? 'primary' : 'secondary'
+            }
           />
         );
       } else {
@@ -426,12 +457,17 @@ const CompactPropertiesEditor = ({
               label={getFieldLabel({ instances, field })}
               markdownDescription={getFieldDescription(field)}
               field={<CompactSemiControlledTextField {...otherCommonProps} />}
+              labelColor={
+                isFieldHighlighted({ instances, field })
+                  ? 'primary'
+                  : 'secondary'
+              }
             />
           );
         }
       }
     },
-    [instances, onFieldChanged, getFieldDescription]
+    [instances, getFieldDescription, onFieldChanged]
   );
 
   const renderSelectField = React.useCallback(
@@ -457,7 +493,7 @@ const CompactPropertiesEditor = ({
         compactSelectField = (
           <CompactSelectField
             key={field.name}
-            value={getFieldValue({ instances, field })}
+            value={'' + getFieldValue({ instances, field })}
             id={field.name}
             onChange={(newValue: string) => {
               instances.forEach(i => setValue(i, parseFloat(newValue) || 0));
@@ -466,7 +502,7 @@ const CompactPropertiesEditor = ({
                 hasImpactOnAllOtherFields: field.hasImpactOnAllOtherFields,
               });
             }}
-            disabled={field.disabled}
+            disabled={getDisabled({ instances, field })}
           >
             {children}
           </CompactSelectField>
@@ -507,10 +543,13 @@ const CompactPropertiesEditor = ({
           label={getFieldLabel({ instances, field })}
           markdownDescription={getFieldDescription(field)}
           field={compactSelectField}
+          labelColor={
+            isFieldHighlighted({ instances, field }) ? 'primary' : 'secondary'
+          }
         />
       );
     },
-    [instances, onFieldChanged, getFieldDescription]
+    [instances, getFieldDescription, onFieldChanged]
   );
 
   const renderButton = React.useCallback(
@@ -619,6 +658,9 @@ const CompactPropertiesEditor = ({
             }}
           />
         }
+        labelColor={
+          isFieldHighlighted({ instances, field }) ? 'primary' : 'secondary'
+        }
       />
     );
   };
@@ -652,6 +694,9 @@ const CompactPropertiesEditor = ({
             }}
           />
         }
+        labelColor={
+          isFieldHighlighted({ instances, field }) ? 'primary' : 'secondary'
+        }
       />
     );
   };
diff --git a/newIDE/app/src/EffectsList/EnumerateEffects.js b/newIDE/app/src/EffectsList/EnumerateEffects.js
index 10c96fc68..7dfc62177 100644
--- a/newIDE/app/src/EffectsList/EnumerateEffects.js
+++ b/newIDE/app/src/EffectsList/EnumerateEffects.js
@@ -40,7 +40,6 @@ export const enumerateEffectsMetadata = (
           // Convert the effect type properties to a PropertiesEditor Schema.
           const parametersSchema: Schema = effectPropertiesMapToSchema({
             defaultValueProperties: effectMetadata.getProperties(),
-            getProperties: instance => effectMetadata.getProperties(),
           });
           return {
             extension,
diff --git a/newIDE/app/src/InstancesEditor/CompactInstancePropertiesEditor/index.js b/newIDE/app/src/InstancesEditor/CompactInstancePropertiesEditor/index.js
index 0065a547d..66a8adf14 100644
--- a/newIDE/app/src/InstancesEditor/CompactInstancePropertiesEditor/index.js
+++ b/newIDE/app/src/InstancesEditor/CompactInstancePropertiesEditor/index.js
@@ -31,9 +31,28 @@ import TileSetVisualizer, {
   type TileMapTileSelection,
 } from '../TileSetVisualizer';
 import Add from '../../UI/CustomSvgIcons/Add';
+import {
+  TopLevelCollapsibleSection,
+  CollapsibleSubPanel,
+  type TitleBarButton,
+} from '../../ObjectEditor/CompactObjectPropertiesEditor';
+import { ColumnStackLayout } from '../../UI/Layout';
+import Link from '../../UI/Link';
+import { CompactBehaviorPropertiesEditor } from '../../ObjectEditor/CompactObjectPropertiesEditor/CompactBehaviorPropertiesEditor';
+import { IconContainer } from '../../UI/IconContainer';
+import { getHelpLink } from '../../Utils/HelpLink';
+import Window from '../../Utils/Window';
+import { type ResourceManagementProps } from '../../ResourcesList/ResourceSource';
+import EmptyMessage from '../../UI/EmptyMessage';
 
 const gd: libGDevelop = global.gd;
 
+const notOverridableBehaviorTypes = [
+  'Physics2::Physics2Behavior',
+  'Physics3D::Physics3DBehavior',
+  'PhysicsBehavior::PhysicsBehavior',
+];
+
 export const styles = {
   icon: {
     fontSize: 18,
@@ -41,14 +60,56 @@ export const styles = {
   scrollView: { paddingTop: marginsSize },
 };
 
+const behaviorsHelpLink = getHelpLink('/behaviors');
+
 const noRefreshOfAllFields = () => {
   console.warn(
     "An instance tried to refresh all fields, but the editor doesn't support it."
   );
 };
 
+export const StatefulCollapsibleSubPanel = ({
+  renderContent,
+  isInitiallyFolded,
+  onToggleFolded,
+  title,
+  titleIcon,
+  titleBarButtons,
+}: {|
+  renderContent: () => React.Node,
+  isInitiallyFolded: boolean,
+  onToggleFolded?: () => void,
+  titleIcon?: ?React.Node,
+  title: string,
+  titleBarButtons?: Array<TitleBarButton>,
+|}) => {
+  const [isFolded, setIsFolded] = React.useState(isInitiallyFolded);
+
+  const toggleFolded = React.useCallback(
+    () => {
+      setIsFolded(isFolded => !isFolded);
+      if (onToggleFolded) {
+        onToggleFolded();
+      }
+    },
+    [onToggleFolded]
+  );
+
+  return (
+    <CollapsibleSubPanel
+      renderContent={renderContent}
+      isFolded={isFolded}
+      toggleFolded={toggleFolded}
+      title={title}
+      titleIcon={titleIcon}
+      titleBarButtons={titleBarButtons}
+    />
+  );
+};
+
 type Props = {|
   project: gdProject,
+  resourceManagementProps: ResourceManagementProps,
   layout?: ?gdLayout,
   objectsContainer: gdObjectsContainer,
   globalObjectsContainer: gdObjectsContainer | null,
@@ -65,12 +126,14 @@ type Props = {|
   tileMapTileSelection: ?TileMapTileSelection,
   onSelectTileMapTile: (?TileMapTileSelection) => void,
   isVariableListLocked: boolean,
+  canOverrideBehaviorProperties: boolean,
 |};
 
 export const CompactInstancePropertiesEditor = ({
   instances,
   i18n,
   project,
+  resourceManagementProps,
   layout,
   objectsContainer,
   globalObjectsContainer,
@@ -85,12 +148,13 @@ export const CompactInstancePropertiesEditor = ({
   tileMapTileSelection,
   onSelectTileMapTile,
   isVariableListLocked,
+  canOverrideBehaviorProperties,
 }: Props) => {
   const forceUpdate = useForceUpdate();
+  const instance = instances[0];
   const variablesListRef = React.useRef<?VariablesListInterface>(null);
 
   const scrollViewRef = React.useRef<?ScrollViewInterface>(null);
-  const instance = instances[0];
   /**
    * TODO: multiple instances support for variables list. Expected behavior should be:
    * - if instances of different objects, do not show
@@ -105,12 +169,18 @@ export const CompactInstancePropertiesEditor = ({
     }
   }, []);
 
-  const { object, instanceSchema } = React.useMemo<{|
+  const { object, instanceSchema, allVisibleBehaviors } = React.useMemo<{|
     object?: gdObject,
     instanceSchema?: Schema,
+    allVisibleBehaviors: Array<string>,
   |}>(
     () => {
-      if (!instance) return { object: undefined, instanceSchema: undefined };
+      if (!instance)
+        return {
+          object: undefined,
+          instanceSchema: undefined,
+          allVisibleBehaviors: [],
+        };
 
       const associatedObjectName = instance.getObjectName();
       const object = getObjectByName(
@@ -122,7 +192,21 @@ export const CompactInstancePropertiesEditor = ({
         globalObjectsContainer || objectsContainer,
         objectsContainer
       );
-      if (!object) return { object: undefined, instanceSchema: undefined };
+      if (!object)
+        return {
+          object: undefined,
+          instanceSchema: undefined,
+          allVisibleBehaviors: [],
+        };
+
+      const allVisibleBehaviors = object
+        .getAllBehaviorNames()
+        .toJSArray()
+        .map(behaviorName => object.getBehavior(behaviorName))
+        .filter(behavior => !behavior.isDefaultBehavior())
+        // We don't keep the behaviors directly because they may be destroyed
+        // if the object is rebuilt from a serialization.
+        .map(behavior => behavior.getName());
 
       const objectMetadata = gd.MetadataProvider.getObjectMetadata(
         project.getCurrentPlatform(),
@@ -142,11 +226,14 @@ export const CompactInstancePropertiesEditor = ({
         properties,
         // We can't access default values for instance custom properties.
         defaultValueProperties: null,
-        getProperties: (instance: gdInitialInstance) =>
-          instance.getCustomProperties(
-            globalObjectsContainer || objectsContainer,
-            objectsContainer
-          ),
+        getPropertyValue: (instance: gdInitialInstance, name: string) =>
+          instance
+            .getCustomProperties(
+              globalObjectsContainer || objectsContainer,
+              objectsContainer
+            )
+            .get(name)
+            .getValue(),
         onUpdateProperty: (instance: gdInitialInstance, name, value) =>
           instance.updateCustomProperty(
             name,
@@ -174,6 +261,7 @@ export const CompactInstancePropertiesEditor = ({
       return {
         object,
         instanceSchema,
+        allVisibleBehaviors,
       };
     },
     [
@@ -189,6 +277,10 @@ export const CompactInstancePropertiesEditor = ({
     ]
   );
 
+  const [isBehaviorsFolded, setIsBehaviorsFolded] = React.useState(
+    object ? !instance.hasAnyOverriddenProperty(object) : true
+  );
+
   const shouldDisplayTileSetVisualizer =
     !!object && object.getType() === 'TileMap::SimpleTileMap';
 
@@ -263,6 +355,113 @@ export const CompactInstancePropertiesEditor = ({
               </Column>
             </>
           )}
+          {object && canOverrideBehaviorProperties ? (
+            <TopLevelCollapsibleSection
+              title={<Trans>Behaviors</Trans>}
+              isFolded={isBehaviorsFolded}
+              toggleFolded={() => setIsBehaviorsFolded(!isBehaviorsFolded)}
+              renderContent={() => (
+                <ColumnStackLayout noMargin>
+                  {!allVisibleBehaviors.length && (
+                    <Text size="body2" align="center" color="secondary">
+                      <Trans>
+                        There are no{' '}
+                        <Link
+                          href={behaviorsHelpLink}
+                          onClick={() =>
+                            Window.openExternalURL(behaviorsHelpLink)
+                          }
+                        >
+                          behaviors
+                        </Link>{' '}
+                        on this object instance.
+                      </Trans>
+                    </Text>
+                  )}
+                  {allVisibleBehaviors.map(behaviorName => {
+                    const behavior = object.getBehavior(behaviorName);
+                    const behaviorTypeName = behavior.getTypeName();
+                    const behaviorMetadata = gd.MetadataProvider.getBehaviorMetadata(
+                      gd.JsPlatform.get(),
+                      behaviorTypeName
+                    );
+                    const behaviorOverriding = instance.hasBehaviorOverridingNamed(
+                      behaviorName
+                    )
+                      ? instance.getBehaviorOverriding(behaviorName)
+                      : null;
+
+                    const iconUrl = behaviorMetadata.getIconFilename();
+
+                    return (
+                      <StatefulCollapsibleSubPanel
+                        key={behavior.ptr}
+                        renderContent={
+                          notOverridableBehaviorTypes.includes(
+                            behavior.getTypeName()
+                          )
+                            ? () => (
+                                <Column expand>
+                                  <EmptyMessage>
+                                    <Trans>
+                                      This behavior can't be setup per instance.
+                                    </Trans>
+                                  </EmptyMessage>
+                                </Column>
+                              )
+                            : () => (
+                                <CompactBehaviorPropertiesEditor
+                                  project={project}
+                                  behaviorMetadata={behaviorMetadata}
+                                  behavior={behavior}
+                                  behaviorOverriding={behaviorOverriding}
+                                  object={object}
+                                  initialInstance={instance}
+                                  onBehaviorUpdated={() => {
+                                    if (
+                                      instance.hasBehaviorOverridingNamed(
+                                        behaviorName
+                                      ) &&
+                                      !instance.hasAnyOverriddenPropertyForBehavior(
+                                        behavior
+                                      )
+                                    ) {
+                                      instance.removeBehaviorOverriding(
+                                        behaviorName
+                                      );
+                                      // Update the view to stop using
+                                      // the removed behavior overriding.
+                                      forceUpdate();
+                                    }
+                                  }}
+                                  resourceManagementProps={
+                                    resourceManagementProps
+                                  }
+                                />
+                              )
+                        }
+                        isInitiallyFolded={
+                          !instance.hasAnyOverriddenPropertyForBehavior(
+                            behavior
+                          )
+                        }
+                        titleIcon={
+                          iconUrl ? (
+                            <IconContainer
+                              src={iconUrl}
+                              alt={behaviorMetadata.getFullName()}
+                              size={16}
+                            />
+                          ) : null
+                        }
+                        title={behavior.getName()}
+                      />
+                    );
+                  })}
+                </ColumnStackLayout>
+              )}
+            />
+          ) : null}
           {object && shouldDisplayVariablesList ? (
             <>
               <Separator />
diff --git a/newIDE/app/src/InstancesEditor/InstancesAdder.js b/newIDE/app/src/InstancesEditor/InstancesAdder.js
index 63f0fbac0..366548476 100644
--- a/newIDE/app/src/InstancesEditor/InstancesAdder.js
+++ b/newIDE/app/src/InstancesEditor/InstancesAdder.js
@@ -6,12 +6,14 @@ import { type InstancesEditorSettings } from './InstancesEditorSettings';
 const gd: libGDevelop = global.gd;
 
 export const addSerializedInstances = ({
+  project,
   instancesContainer,
   copyReferential,
   serializedInstances,
   addInstancesInTheForeground = false,
   doesObjectExistInContext,
 }: {|
+  project: gdProject,
   instancesContainer: gdInitialInstancesContainer,
   copyReferential: [number, number],
   serializedInstances: Array<Object>,
@@ -29,7 +31,12 @@ export const addSerializedInstances = ({
   const newInstances = serializedInstances
     .map(serializedInstance => {
       const instance = new gd.InitialInstance();
-      unserializeFromJSObject(instance, serializedInstance);
+      unserializeFromJSObject(
+        instance,
+        serializedInstance,
+        'unserializeFrom',
+        project
+      );
       if (!doesObjectExistInContext(instance.getObjectName())) return null;
       instance.setX(instance.getX() - copyReferential[0]);
       instance.setY(instance.getY() - copyReferential[1]);
@@ -65,6 +72,7 @@ export const addSerializedInstances = ({
 };
 
 type Props = {|
+  project: gdProject,
   instances: gdInitialInstancesContainer,
   instancesEditorSettings: InstancesEditorSettings,
 |};
@@ -74,12 +82,14 @@ type Props = {|
  * which are real instances but can be deleted as long as they are not "committed".
  */
 export default class InstancesAdder {
+  _project: gdProject;
   _instances: gdInitialInstancesContainer;
   _temporaryInstances: Array<gdInitialInstance>;
   _instancesEditorSettings: InstancesEditorSettings;
   _zOrderFinder = new gd.HighestZOrderFinder();
 
-  constructor({ instances, instancesEditorSettings }: Props) {
+  constructor({ project, instances, instancesEditorSettings }: Props) {
+    this._project = project;
     this._instances = instances;
     this._instancesEditorSettings = instancesEditorSettings;
     this._temporaryInstances = [];
@@ -103,6 +113,7 @@ export default class InstancesAdder {
     doesObjectExistInContext: string => boolean,
   |}): Array<gdInitialInstance> => {
     const instances = addSerializedInstances({
+      project: this._project,
       instancesContainer: this._instances,
       copyReferential,
       serializedInstances,
diff --git a/newIDE/app/src/InstancesEditor/index.js b/newIDE/app/src/InstancesEditor/index.js
index cd621ea84..53b49bba0 100644
--- a/newIDE/app/src/InstancesEditor/index.js
+++ b/newIDE/app/src/InstancesEditor/index.js
@@ -431,6 +431,7 @@ export default class InstancesEditor extends Component<Props, State> {
     });
 
     this._instancesAdder = new InstancesAdder({
+      project: this.props.project,
       instances: this.props.initialInstances,
       instancesEditorSettings: this.props.instancesEditorSettings,
     });
diff --git a/newIDE/app/src/ObjectEditor/CompactObjectPropertiesEditor/ChildObjectPropertiesEditor.js b/newIDE/app/src/ObjectEditor/CompactObjectPropertiesEditor/ChildObjectPropertiesEditor.js
index 708ebb994..e1070a9b6 100644
--- a/newIDE/app/src/ObjectEditor/CompactObjectPropertiesEditor/ChildObjectPropertiesEditor.js
+++ b/newIDE/app/src/ObjectEditor/CompactObjectPropertiesEditor/ChildObjectPropertiesEditor.js
@@ -59,8 +59,11 @@ export const ChildObjectPropertiesEditor = ({
       return propertiesMapToSchema({
         properties: childObjectConfigurationAsGd.getProperties(),
         defaultValueProperties: null,
-        getProperties: ({ object, objectConfiguration }) =>
-          objectConfiguration.getProperties(),
+        getPropertyValue: ({ object, objectConfiguration }, name) =>
+          objectConfiguration
+            .getProperties()
+            .get(name)
+            .getValue(),
         onUpdateProperty: ({ object, objectConfiguration }, name, value) =>
           objectConfiguration.updateProperty(name, value),
         visibility: 'All',
diff --git a/newIDE/app/src/ObjectEditor/CompactObjectPropertiesEditor/CompactBehaviorPropertiesEditor.js b/newIDE/app/src/ObjectEditor/CompactObjectPropertiesEditor/CompactBehaviorPropertiesEditor.js
index 0cf7183e2..6025fcc62 100644
--- a/newIDE/app/src/ObjectEditor/CompactObjectPropertiesEditor/CompactBehaviorPropertiesEditor.js
+++ b/newIDE/app/src/ObjectEditor/CompactObjectPropertiesEditor/CompactBehaviorPropertiesEditor.js
@@ -59,6 +59,8 @@ export const CompactBehaviorPropertiesEditor = ({
   behaviorMetadata,
   behavior,
   object,
+  behaviorOverriding,
+  initialInstance,
   onOpenFullEditor,
   onBehaviorUpdated,
   resourceManagementProps,
@@ -67,7 +69,9 @@ export const CompactBehaviorPropertiesEditor = ({
   behaviorMetadata: gdBehaviorMetadata,
   behavior: gdBehavior,
   object: gdObject,
-  onOpenFullEditor: () => void,
+  behaviorOverriding: gdBehavior | null,
+  initialInstance: gdInitialInstance | null,
+  onOpenFullEditor?: () => void,
   onBehaviorUpdated: () => void,
   resourceManagementProps: ResourceManagementProps,
 |}) => {
@@ -80,10 +84,67 @@ export const CompactBehaviorPropertiesEditor = ({
       if (schemaRecomputeTrigger) {
         // schemaRecomputeTrigger allows to invalidate the schema when required.
       }
+      if (initialInstance) {
+        const behaviorProperties = behavior.getProperties();
+        return propertiesMapToSchema({
+          properties: behaviorProperties,
+          defaultValueProperties: behaviorProperties,
+          getPropertyValue: (instance, propertyName) => {
+            const behaviorName = behavior.getName();
+            if (
+              initialInstance.hasBehaviorOverridingNamed(behaviorName) &&
+              initialInstance
+                .getBehaviorOverriding(behaviorName)
+                .hasPropertyValue(propertyName)
+            ) {
+              const behaviorOverriding = initialInstance.getBehaviorOverriding(
+                behaviorName
+              );
+              return behaviorOverriding
+                .getProperties()
+                .get(propertyName)
+                .getValue();
+            }
+            return behavior
+              .getProperties()
+              .get(propertyName)
+              .getValue();
+          },
+          onUpdateProperty: (instance, name, value) => {
+            const behaviorName = behavior.getName();
+            const behaviorOverriding = initialInstance.hasBehaviorOverridingNamed(
+              behaviorName
+            )
+              ? initialInstance.getBehaviorOverriding(behaviorName)
+              : initialInstance.addNewBehaviorOverriding(
+                  project,
+                  behavior.getTypeName(),
+                  behaviorName
+                );
+            const behaviorProperties = behavior.getProperties();
+            const inheritedValue = behaviorProperties.has(name)
+              ? behaviorProperties.get(name).getValue()
+              : null;
+            if (inheritedValue === value) {
+              behaviorOverriding.removeProperty(name);
+            } else {
+              behaviorOverriding.updateProperty(name, value);
+            }
+          },
+          object,
+          visibility: 'All',
+          showcaseNonDefaultValues: true,
+        });
+      }
+      const behaviorMetadataProperties = behaviorMetadata.getProperties();
       return propertiesMapToSchema({
-        properties: behavior.getProperties(),
-        defaultValueProperties: behaviorMetadata.getProperties(),
-        getProperties: instance => instance.getProperties(),
+        properties: behaviorMetadataProperties,
+        defaultValueProperties: behaviorMetadataProperties,
+        getPropertyValue: (instance, name) =>
+          instance
+            .getProperties()
+            .get(name)
+            .getValue(),
         onUpdateProperty: (instance, name, value) => {
           instance.updateProperty(name, value);
         },
@@ -91,7 +152,14 @@ export const CompactBehaviorPropertiesEditor = ({
         visibility: 'All',
       });
     },
-    [schemaRecomputeTrigger, behavior, behaviorMetadata, object]
+    [
+      schemaRecomputeTrigger,
+      initialInstance,
+      behavior,
+      behaviorMetadata,
+      object,
+      project,
+    ]
   );
 
   return (
@@ -104,13 +172,16 @@ export const CompactBehaviorPropertiesEditor = ({
         onInstancesModified={onBehaviorUpdated}
         resourceManagementProps={resourceManagementProps}
         placeholder={<Trans>Nothing to configure for this behavior.</Trans>}
-        customizeBasicSchema={schema =>
-          getSchemaWithOpenFullEditorButton({
-            schema,
-            fullEditorLabel,
-            behavior,
-            onOpenFullEditor,
-          })
+        customizeBasicSchema={
+          onOpenFullEditor
+            ? schema =>
+                getSchemaWithOpenFullEditorButton({
+                  schema,
+                  fullEditorLabel,
+                  behavior,
+                  onOpenFullEditor,
+                })
+            : null
         }
         onRefreshAllFields={forceRecomputeSchema}
       />
diff --git a/newIDE/app/src/ObjectEditor/CompactObjectPropertiesEditor/index.js b/newIDE/app/src/ObjectEditor/CompactObjectPropertiesEditor/index.js
index eeb58ca1e..8ade9e427 100644
--- a/newIDE/app/src/ObjectEditor/CompactObjectPropertiesEditor/index.js
+++ b/newIDE/app/src/ObjectEditor/CompactObjectPropertiesEditor/index.js
@@ -89,14 +89,14 @@ const objectVariablesHelpLink = getHelpLink(
   '/all-features/variables/object-variables'
 );
 
-type TitleBarButton = {|
+export type TitleBarButton = {|
   id: string,
   icon: any,
   label?: MessageDescriptor,
   onClick?: () => void,
 |};
 
-const CollapsibleSubPanel = ({
+export const CollapsibleSubPanel = ({
   renderContent,
   isFolded,
   toggleFolded,
@@ -157,7 +157,7 @@ const CollapsibleSubPanel = ({
   </Paper>
 );
 
-const TopLevelCollapsibleSection = ({
+export const TopLevelCollapsibleSection = ({
   title,
   isFolded,
   toggleFolded,
@@ -173,7 +173,7 @@ const TopLevelCollapsibleSection = ({
   renderContent: () => React.Node,
   renderContentAsHiddenWhenFolded?: boolean,
   noContentMargin?: boolean,
-  onOpenFullEditor: () => void,
+  onOpenFullEditor?: () => void,
   onAdd?: (() => void) | null,
 |}) => (
   <>
@@ -193,9 +193,11 @@ const TopLevelCollapsibleSection = ({
           </Text>
         </LineStackLayout>
         <Line alignItems="center" noMargin>
-          <IconButton size="small" onClick={onOpenFullEditor}>
-            <ShareExternal style={styles.icon} />
-          </IconButton>
+          {onOpenFullEditor && (
+            <IconButton size="small" onClick={onOpenFullEditor}>
+              <ShareExternal style={styles.icon} />
+            </IconButton>
+          )}
           {onAdd && (
             <IconButton size="small" onClick={onAdd}>
               <Add style={styles.icon} />
@@ -492,8 +494,11 @@ export const CompactObjectPropertiesEditor = ({
           ? customObjectEventsBasedObject.getPropertyDescriptors()
           : // We can't access default values for built-in objects.
             null,
-        getProperties: ({ objectConfiguration }) =>
-          objectConfiguration.getProperties(),
+        getPropertyValue: ({ objectConfiguration }, name) =>
+          objectConfiguration
+            .getProperties()
+            .get(name)
+            .getValue(),
         onUpdateProperty: ({ objectConfiguration }, name, value) => {
           objectConfiguration.updateProperty(name, value);
           onObjectsModified([object]);
@@ -749,6 +754,8 @@ export const CompactObjectPropertiesEditor = ({
                           project={project}
                           behaviorMetadata={behaviorMetadata}
                           behavior={behavior}
+                          behaviorOverriding={null}
+                          initialInstance={null}
                           object={object}
                           onBehaviorUpdated={() => {}}
                           resourceManagementProps={resourceManagementProps}
diff --git a/newIDE/app/src/ObjectEditor/Editors/CustomObjectPropertiesEditor/index.js b/newIDE/app/src/ObjectEditor/Editors/CustomObjectPropertiesEditor/index.js
index 3fcd355d6..71875ffe2 100644
--- a/newIDE/app/src/ObjectEditor/Editors/CustomObjectPropertiesEditor/index.js
+++ b/newIDE/app/src/ObjectEditor/Editors/CustomObjectPropertiesEditor/index.js
@@ -439,7 +439,11 @@ const CustomObjectPropertiesEditor = (props: Props) => {
         defaultValueProperties: customObjectEventsBasedObject
           ? customObjectEventsBasedObject.getPropertyDescriptors()
           : null,
-        getProperties: instance => instance.getProperties(),
+        getPropertyValue: (instance, name) =>
+          instance
+            .getProperties()
+            .get(name)
+            .getValue(),
         onUpdateProperty: (instance, name, value) => {
           instance.updateProperty(name, value);
         },
diff --git a/newIDE/app/src/ObjectEditor/Editors/ObjectPropertiesEditor.js b/newIDE/app/src/ObjectEditor/Editors/ObjectPropertiesEditor.js
index 25540f958..9a9dc8a91 100644
--- a/newIDE/app/src/ObjectEditor/Editors/ObjectPropertiesEditor.js
+++ b/newIDE/app/src/ObjectEditor/Editors/ObjectPropertiesEditor.js
@@ -42,7 +42,11 @@ const ObjectPropertiesEditor = (props: Props) => {
   const propertiesSchema = propertiesMapToSchema({
     properties,
     defaultValueProperties: null,
-    getProperties: object => object.getProperties(),
+    getPropertyValue: (object, name) =>
+      object
+        .getProperties()
+        .get(name)
+        .getValue(),
     onUpdateProperty: (object, name, value) =>
       object.updateProperty(name, value),
   });
diff --git a/newIDE/app/src/ObjectsRendering/Renderers/CustomObjectLayoutingModel.js b/newIDE/app/src/ObjectsRendering/Renderers/CustomObjectLayoutingModel.js
index 7661380e6..e7e4bbe89 100644
--- a/newIDE/app/src/ObjectsRendering/Renderers/CustomObjectLayoutingModel.js
+++ b/newIDE/app/src/ObjectsRendering/Renderers/CustomObjectLayoutingModel.js
@@ -39,10 +39,18 @@ export type ObjectAnchor = {
 };
 
 const getPropertyValue = (
+  name: string,
   properties: gdMapStringPropertyDescriptor,
-  name: string
+  behaviorOverriding: gdBehavior | null
 ): CustomObjectConfiguration_EdgeAnchor =>
-  properties.has(name)
+  behaviorOverriding && behaviorOverriding.hasPropertyValue(name)
+    ? gd.CustomObjectConfiguration.getEdgeAnchorFromString(
+        behaviorOverriding
+          .getProperties()
+          .get(name)
+          .getValue()
+      )
+    : properties.has(name)
     ? gd.CustomObjectConfiguration.getEdgeAnchorFromString(
         properties.get(name).getValue()
       )
@@ -64,7 +72,8 @@ const getDefaultAnchor = () => ({
  */
 export const getObjectAnchor = (
   eventBasedObjectVariant: gdEventsBasedObjectVariant,
-  objectName: string
+  objectName: string,
+  initialInstance: gdInitialInstance
 ): ObjectAnchor => {
   const objects = eventBasedObjectVariant.getObjects();
   if (!objects.hasObjectNamed(objectName)) {
@@ -75,10 +84,31 @@ export const getObjectAnchor = (
     return getDefaultAnchor();
   }
   const properties = childObject.getBehavior('Anchor').getProperties();
-  const leftEdgeAnchor = getPropertyValue(properties, 'leftEdgeAnchor');
-  const topEdgeAnchor = getPropertyValue(properties, 'topEdgeAnchor');
-  const rightEdgeAnchor = getPropertyValue(properties, 'rightEdgeAnchor');
-  const bottomEdgeAnchor = getPropertyValue(properties, 'bottomEdgeAnchor');
+  const behaviorOverriding = initialInstance.hasBehaviorOverridingNamed(
+    'Anchor'
+  )
+    ? initialInstance.getBehaviorOverriding('Anchor')
+    : null;
+  const leftEdgeAnchor = getPropertyValue(
+    'leftEdgeAnchor',
+    properties,
+    behaviorOverriding
+  );
+  const topEdgeAnchor = getPropertyValue(
+    'topEdgeAnchor',
+    properties,
+    behaviorOverriding
+  );
+  const rightEdgeAnchor = getPropertyValue(
+    'rightEdgeAnchor',
+    properties,
+    behaviorOverriding
+  );
+  const bottomEdgeAnchor = getPropertyValue(
+    'bottomEdgeAnchor',
+    properties,
+    behaviorOverriding
+  );
   return { leftEdgeAnchor, topEdgeAnchor, rightEdgeAnchor, bottomEdgeAnchor };
 };
 
@@ -274,6 +304,14 @@ export class LayoutedInstance {
     return [];
   }
 
+  hasBehaviorOverridingNamed(name: string): boolean {
+    return this.instance.hasBehaviorOverridingNamed(name);
+  }
+
+  getBehaviorOverriding(name: string): gdBehavior {
+    return this.instance.getBehaviorOverriding(name);
+  }
+
   serializeTo(element: gdSerializerElement) {}
 
   unserializeFrom(element: gdSerializerElement) {}
@@ -337,7 +375,8 @@ export const getLayoutedRenderedInstance = <T: ChildRenderedInstance>(
 
   const objectAnchor = getObjectAnchor(
     eventBasedObjectVariant,
-    layoutedInstance.getObjectName()
+    layoutedInstance.getObjectName(),
+    initialInstance
   );
   const leftEdgeAnchor = objectAnchor
     ? objectAnchor.leftEdgeAnchor
diff --git a/newIDE/app/src/ProjectManager/ExtensionsProperties.js b/newIDE/app/src/ProjectManager/ExtensionsProperties.js
index fc5058ec9..0b16ed5fb 100644
--- a/newIDE/app/src/ProjectManager/ExtensionsProperties.js
+++ b/newIDE/app/src/ProjectManager/ExtensionsProperties.js
@@ -23,10 +23,12 @@ function ExtensionsProperties(props: Props) {
     const propertiesSchema = propertiesMapToSchema({
       properties,
       defaultValueProperties: null,
-      getProperties: instance =>
+      getPropertyValue: (instance, name) =>
         project
           .getExtensionProperties()
-          .getAllExtensionProperties(extension.getName(), project),
+          .getAllExtensionProperties(extension.getName(), project)
+          .get(name)
+          .getValue(),
       onUpdateProperty: (instance, propertyName, newValue) => {
         if (
           project
diff --git a/newIDE/app/src/ProjectManager/ExternalLayoutTreeViewItemContent.js b/newIDE/app/src/ProjectManager/ExternalLayoutTreeViewItemContent.js
index cf38a4cc7..b660f26b0 100644
--- a/newIDE/app/src/ProjectManager/ExternalLayoutTreeViewItemContent.js
+++ b/newIDE/app/src/ProjectManager/ExternalLayoutTreeViewItemContent.js
@@ -199,7 +199,12 @@ export class ExternalLayoutTreeViewItemContent implements TreeViewItemContent {
       this.getIndex() + 1
     );
 
-    unserializeFromJSObject(newExternalLayout, copiedExternalLayout);
+    unserializeFromJSObject(
+      newExternalLayout,
+      copiedExternalLayout,
+      'unserializeFrom',
+      project
+    );
     // Unserialization has overwritten the name.
     newExternalLayout.setName(newName);
 
diff --git a/newIDE/app/src/PropertiesEditor/PropertiesEditorSchema.js b/newIDE/app/src/PropertiesEditor/PropertiesEditorSchema.js
index 059117298..6dd761db3 100644
--- a/newIDE/app/src/PropertiesEditor/PropertiesEditorSchema.js
+++ b/newIDE/app/src/PropertiesEditor/PropertiesEditorSchema.js
@@ -16,6 +16,7 @@ export type ValueFieldCommonProperties = {|
   getLabel?: Instance => string,
   getDescription?: Instance => string,
   hideLabel?: boolean,
+  isHighlighted?: Instance => boolean,
   getExtraDescription?: Instance => string,
   hasImpactOnAllOtherFields?: boolean,
   canBeUnlimitedUsingMinus1?: boolean,
@@ -32,8 +33,13 @@ export type ValueFieldCommonProperties = {|
 export type PrimitiveValueField =
   | {|
       valueType: 'number',
-      getValue: Instance => number,
+      getValue: Instance => number | null,
       setValue: (instance: Instance, newValue: number) => void,
+      getChoices?: ?() => Array<{|
+        value: string,
+        label: string,
+        labelIsUserDefined?: boolean,
+      |}>,
       /** Only supported on non compact property editors. */
       getEndAdornment?: Instance => {|
         label: string,
@@ -46,7 +52,7 @@ export type PrimitiveValueField =
     |}
   | {|
       valueType: 'string',
-      getValue: Instance => string,
+      getValue: Instance => string | null,
       setValue: (instance: Instance, newValue: string) => void,
       getChoices?: ?() => Array<{|
         value: string,
@@ -63,7 +69,7 @@ export type PrimitiveValueField =
     |}
   | {|
       valueType: 'boolean',
-      getValue: Instance => boolean,
+      getValue: Instance => boolean | null,
       setValue: (instance: Instance, newValue: boolean) => void,
       ...ValueFieldCommonProperties,
     |}
diff --git a/newIDE/app/src/PropertiesEditor/PropertiesMapToSchema.js b/newIDE/app/src/PropertiesEditor/PropertiesMapToSchema.js
index 6b13d51bc..8e44db463 100644
--- a/newIDE/app/src/PropertiesEditor/PropertiesMapToSchema.js
+++ b/newIDE/app/src/PropertiesEditor/PropertiesMapToSchema.js
@@ -36,14 +36,11 @@ const createField = (
     value: boolean
   ) => void,
   defaultValue: string | null,
-  getProperties: (instance: Instance) => any,
-  object: ?gdObject
+  object: ?gdObject,
+  showcaseNonDefaultValues: boolean
 ): ?Field => {
-  const propertyDescription = property.getDescription();
+  const propertyName = property.getLabel();
   const getLabel = (instance: Instance) => {
-    const propertyName = getProperties(instance)
-      .get(name)
-      .getLabel();
     if (propertyName) return propertyName;
     return (
       name.charAt(0).toUpperCase() +
@@ -53,17 +50,27 @@ const createField = (
         .join(' ')
     );
   };
+  const propertyDescription = property.getDescription();
   const getDescription = () => propertyDescription;
+
+  const measurementUnit = property.getMeasurementUnit();
+  // TODO Pass this object in the schema instead of building an UI element here.
+  // It will allow to use these data to make a different component for the
+  // compact and regular UI.
+  const enumeratedMeasurementUnit = {
+    shortLabel: getMeasurementUnitShortLabel(measurementUnit),
+    label: measurementUnit.getLabel(),
+    description: measurementUnit.getDescription(),
+    elementsWithWords: measurementUnit.getElementsWithWords(),
+  };
   const getEndAdornment = (instance: Instance) => {
-    const property = getProperties(instance).get(name);
-    const measurementUnit = property.getMeasurementUnit();
     return {
-      label: getMeasurementUnitShortLabel(measurementUnit),
+      label: enumeratedMeasurementUnit.shortLabel,
       tooltipContent: (
         <MeasurementUnitDocumentation
-          label={measurementUnit.getLabel()}
-          description={measurementUnit.getDescription()}
-          elementsWithWords={measurementUnit.getElementsWithWords()}
+          label={enumeratedMeasurementUnit.label}
+          description={enumeratedMeasurementUnit.description}
+          elementsWithWords={enumeratedMeasurementUnit.elementsWithWords}
         />
       ),
     };
@@ -74,16 +81,30 @@ const createField = (
     ? 'advanced'
     : 'basic';
 
+  const getValueForString = (instance: Instance): string =>
+    getStringValue(instance, name);
+  const getValueForNumber = (instance: Instance): number =>
+    getNumberValue(instance, name);
+  const defaultValueNumber =
+    defaultValue !== null ? parseFloat(defaultValue) || 0 : null;
+  const isHighlightedForNumber = (instance: gdInitialInstance) => {
+    return (
+      showcaseNonDefaultValues &&
+      getValueForNumber(instance) !== defaultValueNumber
+    );
+  };
+  const isHighlightedForString = (instance: gdInitialInstance) => {
+    return (
+      showcaseNonDefaultValues && getValueForString(instance) !== defaultValue
+    );
+  };
+
   const valueType = property.getType().toLowerCase();
   if (valueType === 'number') {
-    const defaultValueNumber =
-      defaultValue !== null ? parseFloat(defaultValue) || 0 : null;
-    const getValue = (instance: Instance): number =>
-      getNumberValue(instance, name);
     const getEndAdornmentIcon =
       defaultValueNumber !== null
         ? (instance: gdInitialInstance) => {
-            return getValue(instance) === defaultValueNumber
+            return getValueForNumber(instance) === defaultValueNumber
               ? null
               : className => <Restore className={className} />;
           }
@@ -100,7 +121,7 @@ const createField = (
     return {
       name,
       valueType,
-      getValue,
+      getValue: getValueForNumber,
       setValue,
       defaultValue: defaultValueNumber,
       getLabel,
@@ -114,12 +135,13 @@ const createField = (
       getEndAdornmentIcon,
       onClickEndAdornment,
       visibility,
+      isHighlighted: isHighlightedForNumber,
     };
   } else if (valueType === 'string' || valueType === '') {
     return {
       name,
       valueType: 'string',
-      getValue: (instance: Instance): string => getStringValue(instance, name),
+      getValue: getValueForString,
       setValue: (instance: Instance, newValue: string) => {
         setStringValue(instance, name, newValue);
       },
@@ -128,21 +150,25 @@ const createField = (
       getDescription,
       hasImpactOnAllOtherFields: property.hasImpactOnOtherProperties(),
       visibility,
+      isHighlighted: isHighlightedForString,
     };
   } else if (valueType === 'boolean') {
+    const defaultValueBoolean = defaultValue ? defaultValue === 'true' : null;
+    const getValue = (instance: Instance): boolean =>
+      getBooleanValue(instance, name);
     return {
       name,
       valueType,
-      getValue: (instance: Instance): boolean =>
-        getBooleanValue(instance, name),
+      getValue,
       setValue: (instance: Instance, newValue: boolean) => {
         setBooleanValue(instance, name, newValue);
       },
-      defaultValue: defaultValue ? defaultValue === 'true' : null,
+      defaultValue: defaultValueBoolean,
       getLabel,
       getDescription,
       hasImpactOnAllOtherFields: property.hasImpactOnOtherProperties(),
       visibility,
+      isHighlighted: isHighlightedForString,
     };
   } else if (valueType === 'choice' || valueType === 'numberwithchoices') {
     // Choice is a "string" (with a selector for the user in the UI)
@@ -160,19 +186,35 @@ const createField = (
       .toJSArray()
       .map(value => ({ value, label: value }));
 
-    return {
-      name,
-      valueType: 'string',
-      getChoices: () => [...choices, ...deprecatedChoices],
-      getValue: (instance: Instance): string => getStringValue(instance, name),
-      setValue: (instance: Instance, newValue: string) => {
-        setStringValue(instance, name, newValue);
-      },
-      getLabel,
-      getDescription,
-      hasImpactOnAllOtherFields: property.hasImpactOnOtherProperties(),
-      visibility,
-    };
+    return valueType === 'numberwithchoices'
+      ? {
+          name,
+          valueType: 'number',
+          getChoices: () => [...choices, ...deprecatedChoices],
+          getValue: getValueForNumber,
+          setValue: (instance: Instance, newValue: number) => {
+            setNumberValue(instance, name, newValue);
+          },
+          getLabel,
+          getDescription,
+          hasImpactOnAllOtherFields: property.hasImpactOnOtherProperties(),
+          visibility,
+          isHighlighted: isHighlightedForNumber,
+        }
+      : {
+          name,
+          valueType: 'string',
+          getChoices: () => [...choices, ...deprecatedChoices],
+          getValue: getValueForString,
+          setValue: (instance: Instance, newValue: string) => {
+            setStringValue(instance, name, newValue);
+          },
+          getLabel,
+          getDescription,
+          hasImpactOnAllOtherFields: property.hasImpactOnOtherProperties(),
+          visibility,
+          isHighlighted: isHighlightedForString,
+        };
   } else if (valueType === 'behavior') {
     const behaviorType =
       property.getExtraInfo().size() > 0 ? property.getExtraInfo().at(0) : '';
@@ -202,13 +244,14 @@ const createField = (
       getDescription,
       hasImpactOnAllOtherFields: property.hasImpactOnOtherProperties(),
       visibility,
+      isHighlighted: isHighlightedForString,
     };
   } else if (valueType === 'leaderboardid') {
     // LeaderboardId is a "string" (with a selector in the UI)
     return {
       name,
       valueType: 'leaderboardId',
-      getValue: (instance: Instance): string => getStringValue(instance, name),
+      getValue: getValueForString,
       setValue: (instance: Instance, newValue: string) => {
         setStringValue(instance, name, newValue);
       },
@@ -216,6 +259,7 @@ const createField = (
       getDescription,
       hasImpactOnAllOtherFields: property.hasImpactOnOtherProperties(),
       visibility,
+      isHighlighted: isHighlightedForString,
     };
   } else if (valueType === 'resource') {
     // Resource is a "string" (with a selector in the UI)
@@ -226,7 +270,7 @@ const createField = (
       name,
       valueType: 'resource',
       resourceKind: kind,
-      getValue: (instance: Instance): string => getStringValue(instance, name),
+      getValue: getValueForString,
       setValue: (instance: Instance, newValue: string) => {
         setStringValue(instance, name, newValue);
       },
@@ -234,12 +278,13 @@ const createField = (
       getDescription,
       hasImpactOnAllOtherFields: property.hasImpactOnOtherProperties(),
       visibility,
+      isHighlighted: isHighlightedForString,
     };
   } else if (valueType === 'color') {
     return {
       name,
       valueType: 'color',
-      getValue: (instance: Instance): string => getStringValue(instance, name),
+      getValue: getValueForString,
       setValue: (instance: Instance, newValue: string) => {
         setStringValue(instance, name, newValue);
       },
@@ -247,12 +292,13 @@ const createField = (
       getDescription,
       hasImpactOnAllOtherFields: property.hasImpactOnOtherProperties(),
       visibility,
+      isHighlighted: isHighlightedForString,
     };
   } else if (valueType === 'multilinestring') {
     return {
       name,
       valueType: 'multilinestring',
-      getValue: (instance: Instance): string => getStringValue(instance, name),
+      getValue: getValueForString,
       setValue: (instance: Instance, newValue: string) => {
         setStringValue(instance, name, newValue);
       },
@@ -260,6 +306,7 @@ const createField = (
       getDescription,
       hasImpactOnAllOtherFields: property.hasImpactOnOtherProperties(),
       visibility,
+      isHighlighted: isHighlightedForString,
     };
   } else if (valueType === 'objectanimationname') {
     return {
@@ -285,13 +332,14 @@ const createField = (
       },
       name,
       valueType: 'string',
-      getValue: (instance: Instance): string => getStringValue(instance, name),
+      getValue: getValueForString,
       setValue: (instance: Instance, newValue: string) => {
         setStringValue(instance, name, newValue);
       },
       getLabel,
       getDescription,
       visibility,
+      isHighlighted: isHighlightedForString,
     };
   } else if (valueType === 'keyboardkey') {
     return {
@@ -305,13 +353,14 @@ const createField = (
       },
       name,
       valueType: 'string',
-      getValue: (instance: Instance): string => getStringValue(instance, name),
+      getValue: getValueForString,
       setValue: (instance: Instance, newValue: string) => {
         setStringValue(instance, name, newValue);
       },
       getLabel,
       getDescription,
       visibility,
+      isHighlighted: isHighlightedForString,
     };
   } else {
     console.error(
@@ -426,18 +475,18 @@ type CommonProps = {|
     | gdPropertiesContainer
     | gdMapStringPropertyDescriptor
     | null,
-  getProperties: (instance: Instance) => any,
   object?: ?gdObject,
   visibility?: 'All' | 'Basic' | 'Advanced' | 'Deprecated' | 'Basic-Quick',
   quickCustomizationVisibilities?: gdQuickCustomizationVisibilitiesContainer,
+  showcaseNonDefaultValues?: boolean,
 |};
 
 export const effectPropertiesMapToSchema = ({
   defaultValueProperties,
-  getProperties,
   object,
   visibility = 'All',
   quickCustomizationVisibilities,
+  showcaseNonDefaultValues,
 }: {
   ...CommonProps,
   defaultValueProperties: gdMapStringPropertyDescriptor,
@@ -445,10 +494,10 @@ export const effectPropertiesMapToSchema = ({
   return adaptablePropertiesMapToSchema({
     properties: defaultValueProperties,
     defaultValueProperties,
-    getProperties,
     object,
     visibility,
     quickCustomizationVisibilities,
+    showcaseNonDefaultValues,
     getNumberValue: (instance: Instance, propertyName: string): number =>
       instance.hasDoubleParameter(propertyName)
         ? instance.getDoubleParameter(propertyName)
@@ -493,13 +542,15 @@ export const effectPropertiesMapToSchema = ({
 const propertiesMapToSchema = ({
   properties,
   defaultValueProperties,
-  getProperties,
+  getPropertyValue,
   onUpdateProperty,
   object,
   visibility = 'All',
   quickCustomizationVisibilities,
+  showcaseNonDefaultValues,
 }: {
   ...CommonProps,
+  getPropertyValue: (instance: Instance, propertyName: string) => string,
   properties: gdMapStringPropertyDescriptor,
   onUpdateProperty: (
     instance: Instance,
@@ -510,30 +561,19 @@ const propertiesMapToSchema = ({
   return adaptablePropertiesMapToSchema({
     properties,
     defaultValueProperties,
-    getProperties,
     object,
     visibility,
     quickCustomizationVisibilities,
+    showcaseNonDefaultValues,
     getNumberValue: (instance: Instance, propertyName: string): number => {
-      return (
-        parseFloat(
-          getProperties(instance)
-            .get(propertyName)
-            .getValue()
-        ) || 0
-      ); // Consider a missing value as 0 to avoid propagating NaN.
+      // Consider a missing value as 0 to avoid propagating NaN.
+      return parseFloat(getPropertyValue(instance, propertyName)) || 0;
     },
     getStringValue: (instance: Instance, propertyName: string): string => {
-      return getProperties(instance)
-        .get(propertyName)
-        .getValue();
+      return getPropertyValue(instance, propertyName);
     },
     getBooleanValue: (instance: Instance, propertyName: string): boolean => {
-      return (
-        getProperties(instance)
-          .get(propertyName)
-          .getValue() === 'true'
-      );
+      return getPropertyValue(instance, propertyName) === 'true';
     },
     setNumberValue: (instance: Instance, propertyName: string, value: number) =>
       onUpdateProperty(instance, propertyName, '' + value),
@@ -550,10 +590,10 @@ const propertiesMapToSchema = ({
 const adaptablePropertiesMapToSchema = ({
   properties,
   defaultValueProperties,
-  getProperties,
   object,
   visibility = 'All',
   quickCustomizationVisibilities,
+  showcaseNonDefaultValues,
   getNumberValue,
   getStringValue,
   getBooleanValue,
@@ -684,8 +724,8 @@ const adaptablePropertiesMapToSchema = ({
               setStringValue,
               setBooleanValue,
               rowPropertyDefaultValue,
-              getProperties,
-              object
+              object,
+              !!showcaseNonDefaultValues
             );
 
             if (field) {
@@ -720,8 +760,8 @@ const adaptablePropertiesMapToSchema = ({
             ? defaultValueProperties.get(name).getValue()
             : ''
           : null,
-        getProperties,
-        object
+        object,
+        !!showcaseNonDefaultValues
       );
     }
     if (field) {
diff --git a/newIDE/app/src/PropertiesEditor/index.js b/newIDE/app/src/PropertiesEditor/index.js
index d60140673..d750aa67b 100644
--- a/newIDE/app/src/PropertiesEditor/index.js
+++ b/newIDE/app/src/PropertiesEditor/index.js
@@ -406,7 +406,7 @@ const PropertiesEditor = ({
         const { setValue } = field;
         return (
           <SelectField
-            value={getFieldValue({ instances, field })}
+            value={'' + getFieldValue({ instances, field })}
             key={field.name}
             id={field.name}
             floatingLabelText={getFieldLabel({ instances, field })}
@@ -416,7 +416,7 @@ const PropertiesEditor = ({
               _onInstancesModified(instances);
             }}
             style={styles.field}
-            disabled={field.disabled}
+            disabled={getDisabled({ instances, field })}
           >
             {children}
           </SelectField>
diff --git a/newIDE/app/src/QuickCustomization/QuickBehaviorsTweaker.js b/newIDE/app/src/QuickCustomization/QuickBehaviorsTweaker.js
index 1003748a6..042846962 100644
--- a/newIDE/app/src/QuickCustomization/QuickBehaviorsTweaker.js
+++ b/newIDE/app/src/QuickCustomization/QuickBehaviorsTweaker.js
@@ -37,7 +37,11 @@ const QuickBehaviorPropertiesEditor = ({
       return propertiesMapToSchema({
         properties: behavior.getProperties(),
         defaultValueProperties: null,
-        getProperties: behavior => behavior.getProperties(),
+        getPropertyValue: (behavior, name) =>
+          behavior
+            .getProperties()
+            .get(name)
+            .getValue(),
         onUpdateProperty: (behavior, name, value) => {
           behavior.updateProperty(name, value);
         },
diff --git a/newIDE/app/src/QuickCustomization/QuickTitleTweaker.js b/newIDE/app/src/QuickCustomization/QuickTitleTweaker.js
index 2d1171af7..bde4425ec 100644
--- a/newIDE/app/src/QuickCustomization/QuickTitleTweaker.js
+++ b/newIDE/app/src/QuickCustomization/QuickTitleTweaker.js
@@ -58,7 +58,11 @@ const QuickObjectPropertiesEditor = ({
       const schema = propertiesMapToSchema({
         properties,
         defaultValueProperties: null,
-        getProperties: object => object.getProperties(),
+        getPropertyValue: (object, name) =>
+          object
+            .getProperties()
+            .get(name)
+            .getValue(),
         onUpdateProperty: (object, name, value) =>
           object.updateProperty(name, value),
         object,
diff --git a/newIDE/app/src/ResourcesEditor/ResourcePropertiesEditor/index.js b/newIDE/app/src/ResourcesEditor/ResourcePropertiesEditor/index.js
index 391b90afb..78c984e0f 100644
--- a/newIDE/app/src/ResourcesEditor/ResourcePropertiesEditor/index.js
+++ b/newIDE/app/src/ResourcesEditor/ResourcePropertiesEditor/index.js
@@ -157,7 +157,11 @@ const ResourcePropertiesEditor = React.forwardRef<
         const resourceSchema = propertiesMapToSchema({
           properties,
           defaultValueProperties: null,
-          getProperties: resource => resource.getProperties(),
+          getPropertyValue: (resource, name) =>
+            resource
+              .getProperties()
+              .get(name)
+              .getValue(),
           onUpdateProperty: (resource, name, value) => {
             resource.updateProperty(name, value);
             forceUpdate();
diff --git a/newIDE/app/src/SceneEditor/BehaviorSharedPropertiesEditor.js b/newIDE/app/src/SceneEditor/BehaviorSharedPropertiesEditor.js
index 3541d5d03..8fbf30de7 100644
--- a/newIDE/app/src/SceneEditor/BehaviorSharedPropertiesEditor.js
+++ b/newIDE/app/src/SceneEditor/BehaviorSharedPropertiesEditor.js
@@ -23,7 +23,11 @@ export default class BehaviorSharedPropertiesEditor extends React.Component<Prop
     const propertiesSchema = propertiesMapToSchema({
       properties: behaviorSharedData.getProperties(),
       defaultValueProperties: null,
-      getProperties: behavior => behavior.getProperties(),
+      getPropertyValue: (behavior, name) =>
+        behavior
+          .getProperties()
+          .get(name)
+          .getValue(),
       onUpdateProperty: (behavior, name, value) => {
         behavior.updateProperty(name, value);
       },
diff --git a/newIDE/app/src/SceneEditor/CustomObjectExtractor/CustomObjectExtractor.js b/newIDE/app/src/SceneEditor/CustomObjectExtractor/CustomObjectExtractor.js
index e5f88ff6d..6a1fbc376 100644
--- a/newIDE/app/src/SceneEditor/CustomObjectExtractor/CustomObjectExtractor.js
+++ b/newIDE/app/src/SceneEditor/CustomObjectExtractor/CustomObjectExtractor.js
@@ -77,7 +77,12 @@ export const extractAsCustomObject = ({
   let isRenderedIn3D = null;
   for (const serializedInstance of serializedSelection) {
     const instance = new gd.InitialInstance();
-    unserializeFromJSObject(instance, serializedInstance);
+    unserializeFromJSObject(
+      instance,
+      serializedInstance,
+      'unserializeFrom',
+      project
+    );
     layer = instance.getLayer();
     zOrder = Math.max(zOrder, instance.getZOrder());
 
diff --git a/newIDE/app/src/SceneEditor/InstanceOrObjectPropertiesEditorContainer.js b/newIDE/app/src/SceneEditor/InstanceOrObjectPropertiesEditorContainer.js
index c75e65f78..c38b9b38f 100644
--- a/newIDE/app/src/SceneEditor/InstanceOrObjectPropertiesEditorContainer.js
+++ b/newIDE/app/src/SceneEditor/InstanceOrObjectPropertiesEditorContainer.js
@@ -175,8 +175,10 @@ export const InstanceOrObjectPropertiesEditorContainer = React.forwardRef<
           layersContainer={layersContainer}
           project={project}
           projectScopedContainersAccessor={projectScopedContainersAccessor}
+          resourceManagementProps={resourceManagementProps}
           unsavedChanges={unsavedChanges}
           i18n={i18n}
+          canOverrideBehaviorProperties={!!eventsFunctionsExtension}
         />
       ) : !!objects.length && lastSelectionType === 'object' ? (
         <CompactObjectPropertiesEditor
diff --git a/newIDE/app/src/SceneEditor/ScenePropertiesDialog.js b/newIDE/app/src/SceneEditor/ScenePropertiesDialog.js
index 0a3fd0b17..f0c1cdff8 100644
--- a/newIDE/app/src/SceneEditor/ScenePropertiesDialog.js
+++ b/newIDE/app/src/SceneEditor/ScenePropertiesDialog.js
@@ -164,7 +164,11 @@ const ScenePropertiesDialog = ({
         defaultValueProperties: behaviorMetadata
           ? behaviorMetadata.getSharedProperties()
           : null,
-        getProperties: sharedDataContent => behaviorSharedData.getProperties(),
+        getPropertyValue: (sharedDataContent, name) =>
+          behaviorSharedData
+            .getProperties()
+            .get(name)
+            .getValue(),
         onUpdateProperty: (sharedDataContent, name, value) => {
           behaviorSharedData.updateProperty(name, value);
         },
diff --git a/newIDE/app/src/SceneEditor/index.js b/newIDE/app/src/SceneEditor/index.js
index 513353797..fd06835a2 100644
--- a/newIDE/app/src/SceneEditor/index.js
+++ b/newIDE/app/src/SceneEditor/index.js
@@ -571,7 +571,12 @@ export default class SceneEditor extends React.Component<Props, State> {
 
     const justAddedInstances = changes.addedInstances.map(addedInstance => {
       const instance: gdInitialInstance = this.props.initialInstances.insertNewInitialInstance();
-      unserializeFromJSObject(instance, addedInstance);
+      unserializeFromJSObject(
+        instance,
+        addedInstance,
+        'unserializeFrom',
+        this.props.project
+      );
       return instance;
     });
     if (justAddedInstances.length) {
@@ -2416,6 +2421,7 @@ export default class SceneEditor extends React.Component<Props, State> {
       .map(instance => serializeToJSObject(instance));
 
     const newInstances = addSerializedInstances({
+      project: this.props.project,
       instancesContainer: this.props.initialInstances,
       copyReferential: [-2 * MOVEMENT_BIG_DELTA, -2 * MOVEMENT_BIG_DELTA],
       serializedInstances: serializedSelection,
@@ -2452,6 +2458,7 @@ export default class SceneEditor extends React.Component<Props, State> {
     if (x === null || y === null || instancesContent === null) return;
 
     const newInstances = addSerializedInstances({
+      project: this.props.project,
       instancesContainer: this.props.initialInstances,
       copyReferential: [x, y],
       serializedInstances: instancesContent,
@@ -2517,7 +2524,12 @@ export default class SceneEditor extends React.Component<Props, State> {
 
     for (const serializedInstance of serializedSelection) {
       const instance = new gd.InitialInstance();
-      unserializeFromJSObject(instance, serializedInstance);
+      unserializeFromJSObject(
+        instance,
+        serializedInstance,
+        'unserializeFrom',
+        project
+      );
       newExternalLayout
         .getInitialInstances()
         .insertInitialInstance(instance)
diff --git a/newIDE/app/src/UI/CompactTextAreaField/index.js b/newIDE/app/src/UI/CompactTextAreaField/index.js
index 109b4430c..3327d04bf 100644
--- a/newIDE/app/src/UI/CompactTextAreaField/index.js
+++ b/newIDE/app/src/UI/CompactTextAreaField/index.js
@@ -18,7 +18,6 @@ const styles = {
     textOverflow: 'ellipsis',
     lineHeight: '17px',
     maxHeight: 34, // 2 * lineHeight to limit to 2 lines.
-    opacity: 0.7,
   },
 };
 
@@ -34,6 +33,7 @@ export type CompactTextAreaFieldProps = {|
   placeholder?: MessageDescriptor,
   rows?: number,
   maxLength?: number,
+  labelColor?: 'primary' | 'secondary',
 |};
 
 export const CompactTextAreaField = ({
@@ -48,6 +48,7 @@ export const CompactTextAreaField = ({
   rows,
   maxLength,
   onSubmit,
+  labelColor,
 }: CompactTextAreaFieldProps) => {
   const idToUse = React.useRef<string>(id || makeTimestampedId());
 
@@ -87,7 +88,11 @@ export const CompactTextAreaField = ({
                 },
               }}
             >
-              <Text noMargin style={styles.label}>
+              <Text
+                noMargin
+                style={styles.label}
+                color={labelColor === 'primary' ? 'primary' : 'secondary'}
+              >
                 {label}
               </Text>
             </Tooltip>
diff --git a/newIDE/app/src/UI/CompactToggleField/index.js b/newIDE/app/src/UI/CompactToggleField/index.js
index e5df300cc..4d5f1eecd 100644
--- a/newIDE/app/src/UI/CompactToggleField/index.js
+++ b/newIDE/app/src/UI/CompactToggleField/index.js
@@ -24,7 +24,7 @@ type Props = {|
   disabled?: boolean,
   fullWidth?: boolean,
   hideTooltip?: boolean,
-  labelColor?: 'primary',
+  labelColor?: 'primary' | 'secondary',
 |};
 
 export const CompactToggleField = (props: Props) => {
diff --git a/newIDE/app/src/stories/componentStories/LayoutEditor/CompactInstancePropertiesEditor.stories.js b/newIDE/app/src/stories/componentStories/LayoutEditor/CompactInstancePropertiesEditor.stories.js
index 46ca65af7..cacaedadf 100644
--- a/newIDE/app/src/stories/componentStories/LayoutEditor/CompactInstancePropertiesEditor.stories.js
+++ b/newIDE/app/src/stories/componentStories/LayoutEditor/CompactInstancePropertiesEditor.stories.js
@@ -11,6 +11,7 @@ import paperDecorator from '../../PaperDecorator';
 import { CompactInstancePropertiesEditor } from '../../../InstancesEditor/CompactInstancePropertiesEditor';
 import SerializedObjectDisplay from '../../SerializedObjectDisplay';
 import DragAndDropContextProvider from '../../../UI/DragAndDrop/DragAndDropContextProvider';
+import fakeResourceManagementProps from '../../FakeResourceManagement';
 
 export default {
   title: 'LayoutEditor/CompactInstancePropertiesEditor',
@@ -36,10 +37,14 @@ export const InstanceSprite2d = () => (
             instances={[testProject.testSpriteObjectInstance]}
             editInstanceVariables={action('edit instance variables')}
             onGetInstanceSize={() => [100, 101, 102]}
-            editObjectInPropertiesPanel={action('edit object')}
+            editObjectInPropertiesPanel={action(
+              'edit object in property panel'
+            )}
             tileMapTileSelection={null}
             onSelectTileMapTile={() => {}}
             isVariableListLocked={false}
+            canOverrideBehaviorProperties={true}
+            resourceManagementProps={fakeResourceManagementProps}
           />
         </SerializedObjectDisplay>
       )}
@@ -65,10 +70,14 @@ export const InstanceCube3d = () => (
             instances={[testProject.testLayoutInstance2]}
             editInstanceVariables={action('edit instance variables')}
             onGetInstanceSize={() => [100, 101, 102]}
-            editObjectInPropertiesPanel={action('edit object')}
+            editObjectInPropertiesPanel={action(
+              'edit object in property panel'
+            )}
             tileMapTileSelection={null}
             onSelectTileMapTile={() => {}}
             isVariableListLocked={false}
+            canOverrideBehaviorProperties={true}
+            resourceManagementProps={fakeResourceManagementProps}
           />
         </SerializedObjectDisplay>
       )}
@@ -94,10 +103,14 @@ export const InstanceTextInput = () => (
             instances={[testProject.testLayoutInstance3]}
             editInstanceVariables={action('edit instance variables')}
             onGetInstanceSize={() => [120, 40, 0]}
-            editObjectInPropertiesPanel={action('edit object')}
+            editObjectInPropertiesPanel={action(
+              'edit object in property panel'
+            )}
             tileMapTileSelection={null}
             onSelectTileMapTile={() => {}}
             isVariableListLocked={false}
+            canOverrideBehaviorProperties={true}
+            resourceManagementProps={fakeResourceManagementProps}
           />
         </SerializedObjectDisplay>
       )}