diff --git a/src/Add-on/DrawBoard/ActivityLayerBoardTool.ts b/src/Add-on/DrawBoard/ActivityLayerBoardTool.ts
index e2594ed26..fe6c32f08 100644
--- a/src/Add-on/DrawBoard/ActivityLayerBoardTool.ts
+++ b/src/Add-on/DrawBoard/ActivityLayerBoardTool.ts
@@ -278,12 +278,13 @@ class ActivityLayerBoardTool
     private AppendBoard(br: Board, brNailMap: WeakMap<CylinderHole, Board>, nails: CylinderHole[])
     {
         let oldNailIds = br.LayerNails.filter(n => n?.Object);
+        this.HandleNailList(nails, oldNailIds, brNailMap);
         for (let i = nails.length; i < oldNailIds.length; i++)
             oldNailIds[i]?.Object?.Erase();
-
         for (let i = 0; i < nails.length; i++)
         {
             let nId: ObjectId;
+            let otherBoard = brNailMap.get(nails[i]);
             if (i < oldNailIds.length)
             {
                 let nail = oldNailIds[i].Object as CylinderHole;
@@ -301,13 +302,55 @@ class ActivityLayerBoardTool
                 br.Db.ModelSpace.Append(nails[i]);
                 nId = nails[i].Id;
                 br.AppendNails([nId]);
-                let otherBoard = brNailMap.get(nails[i]);
                 nails[i].MId = br.Id;
                 nails[i].FId = otherBoard.Id;
                 otherBoard.AppendNails([nId]);
             }
         }
     }
+    private HandleNailList(newNails: CylinderHole[], oldNails: ObjectId[], naiMap: WeakMap<CylinderHole, Board>)
+    {
+        if (oldNails.length < newNails.length)
+        {
+            let temp: CylinderHole[] = [];
+            for (let i = 0; i < oldNails.length; i++)
+            {
+                let nail = oldNails[i].Object as CylinderHole;
+                if (newNails.length === 0) break;
+                let j = 0;
+                for (; j < newNails.length; j++)
+                {
+                    let newNail = newNails[j] as CylinderHole;
+                    let otherBoard = naiMap.get(newNail);
+                    if (otherBoard.Id === nail.FId)
+                        break;
+                }
+                if (j < newNails.length)
+                    temp.push(...newNails.splice(j, 1));
+            }
+            newNails.unshift(...temp);
+        }
+        else
+        {
+            let temp: ObjectId[] = [];
+
+            for (let i = 0; i < newNails.length; i++)
+            {
+                let nail = newNails[i];
+                let otherBoard = naiMap.get(nail);
+                let j = 0;
+                for (; j < oldNails.length; j++)
+                {
+                    let oldNail = oldNails[j].Object as CylinderHole;
+                    if (oldNail.FId === otherBoard.Id)
+                        break;
+                }
+                if (j < oldNails.length)
+                    temp.push(...oldNails.splice(j, 1));
+            }
+            oldNails.unshift(...temp);
+        }
+    }
 }
 
 export const activityLayerBoardTool = new ActivityLayerBoardTool();