diff --git a/src/components/ConcernementMapItem.vue b/src/components/ConcernementMapItem.vue
index 20003d3..6d0f1be 100644
--- a/src/components/ConcernementMapItem.vue
+++ b/src/components/ConcernementMapItem.vue
@@ -2150,36 +2150,8 @@ export default {
             // Matter.Body.scale(this.body, obj.s, obj.s)
             this.paper_main_object.scale(obj.s);
 
-            // update superposition constraints points poisitions
-            if (this.concernement.superposition_constraints_id 
-              && this.concernement.superposition_constraints_id[this.id] 
-              && this.concernement.superposition_constraints_id[this.id].length)
-            {
-              // get all the constraints of the world
-              let all_constrains = Matter.Composite.allConstraints(this.matterEngine.world);
-              // loop through all constraint ids recorded in the concernement
-              // get only the constraint of this concernement mapitem
-              for(let constraint_id of this.concernement.superposition_constraints_id[this.id]) {
-                // get the right constraint object from matter
-                let constraint;
-                for (const c of all_constrains) {
-                 if (c.id === constraint_id) {
-                  constraint = c;
-                  break;
-                 } 
-                }  
-                if (constraint) {
-                  // tween the constraint point
-                  let ab = this.cid === constraint.concernementA.id ? 'A' : 'B';
-                  let point = constraint[`point${ab}`];
-                  // revert to the original point
-                  let oripoint = Matter.Vector.create(point.x / this.scale, point.y / this.scale)
-                  // newpoint from original point
-                  let newpoint = Matter.Vector.create(oripoint.x * obj.s, oripoint.y * obj.s)
-                  constraint[`point${ab}`] = newpoint;
-                }
-              }
-            }
+            // update superposition constraints points positions
+            this.resetSuperpositionsConstraintsScaling(obj.s);
 
             // record new scale
             this.prev_scale = this.scale;
@@ -2298,6 +2270,37 @@ export default {
       }
       this.tween.easing(Tween.Easing.Quadratic.InOut).start();
     },
+    resetSuperpositionsConstraintsScaling(s){
+      if (this.concernement.superposition_constraints_id 
+        && this.concernement.superposition_constraints_id[this.id] 
+        && this.concernement.superposition_constraints_id[this.id].length)
+      {
+        // get all the constraints of the world
+        let all_constrains = Matter.Composite.allConstraints(this.matterEngine.world);
+        // loop through all constraint ids recorded in the concernement
+        // get only the constraint of this concernement mapitem
+        for(let constraint_id of this.concernement.superposition_constraints_id[this.id]) {
+          // get the right constraint object from matter
+          let constraint;
+          for (const c of all_constrains) {
+            if (c.id === constraint_id) {
+            constraint = c;
+            break;
+            } 
+          }  
+          if (constraint) {
+            // tween the constraint point
+            let ab = this.cid === constraint.concernementA.id ? 'A' : 'B';
+            let point = constraint[`point${ab}`];
+            // revert to the original point
+            let oripoint = Matter.Vector.create(point.x / this.scale, point.y / this.scale)
+            // newpoint from original point
+            let newpoint = Matter.Vector.create(oripoint.x * s, oripoint.y * s)
+            constraint[`point${ab}`] = newpoint;
+          }
+        }
+      }
+    },
     async resetMapItemPosition(){
       await nextTick();
       console.log('resetMapItemPosition');
@@ -2317,9 +2320,10 @@ export default {
       this.paper_main_object.scale(1 / this.scale);
       // then scale again to new scale
       this.paper_main_object.scale(s);
-      this.prev_scale = this.scale = s;
-
       // TODO handle superposition scaling
+      this.resetSuperpositionsConstraintsScaling(s);
+      // record the new scale
+      this.prev_scale = this.scale = s;
     },
     // ENGINE UPDATE
     onBeforeEngineUpdate (event) {