diff --git a/assembler/annotation.h b/assembler/annotation.h
index 0aa8ba2..8e35d0e 100644
--- a/assembler/annotation.h
+++ b/assembler/annotation.h
@@ -60,6 +60,26 @@ public:
         elements_.push_back(std::forward<AnnotationElement>(element));
     }
 
+    void SetOrAddElementByIndex(size_t ele_idx, AnnotationElement &&element)
+    {
+        // did not find a simple way to replace element directly because of circular dependency of class definition
+        auto len = elements_.size();
+        ASSERT(ele_idx <= len);
+        if (ele_idx == len) {
+            AddElement(std::move(element));
+            return;
+        }
+        std::vector<AnnotationElement> eles;
+        for (size_t i = 0; i < ele_idx; i++) {
+            eles.push_back(std::forward<AnnotationElement>(elements_[i]));
+        }
+        eles.push_back(std::forward<AnnotationElement>(element));
+        for (size_t i = ele_idx + 1; i < len; i++) {
+            eles.push_back(std::forward<AnnotationElement>(elements_[i]));
+        }
+        elements_ = std::forward<std::vector<AnnotationElement>>(eles);
+    }
+
 private:
     std::string record_name_;
     std::vector<AnnotationElement> elements_;
diff --git a/assembler/meta.h b/assembler/meta.h
index 192af07..a613d4a 100644
--- a/assembler/meta.h
+++ b/assembler/meta.h
@@ -207,6 +207,12 @@ public:
         annotations_.insert(annotations_.end(), annotations.begin(), annotations.end());
     }
 
+    void SetOrAddAnnotationElementByIndex(size_t anno_idx, size_t ele_idx, AnnotationElement &&element)
+    {
+        ASSERT(anno_idx < annotations_.size());
+        annotations_[anno_idx].SetOrAddElementByIndex(ele_idx, std::forward<AnnotationElement>(element));
+    }
+
     std::optional<Error> ValidateData() override;
 
 protected: