C# transfer reference of object

Hi,

how can I "transfer" or "relink" an reference of an object from one to another?

Background: I have a script Bar on an prefab gameobject with 2 array fields: Item and CdControl (both classes from me too). The Item hold information such icon, cooldown, etc and the CdControl is a script which controls its prefab-gameobject for showing cooldowns and icons from the Items in the Bar. I instantiate the CdObjects where the CdControl script is attached as CdControl and store them in the first array. This happens in the Awake() Monobehaviour when I instantiate the Bars (because there are no constructors in Unity).

At this point I can walk in a dummy environment with some gameobjects with the Item-scrip attached. I can pick up Items, then they are placed in the Bars and I can use them (cooldowns and Icons updated).

Now I want to make the a drag and drop routine for the Items, so that Items can be moved to other slots in the Bar. To achieve this, I want to relink the reference from the dragged Item to the drop-slot. The code below don't work :(

 //get coordinates normalized on iconsize
     Vector2 MouseGridCoords() {
         return Input.mousePosition/gridTileSize; //for testing this is ok, later we need an offset
     }
     
     //drag and drop items between bars
     void DragAndDropItems() {
         //drag
         if (Input.GetMouseButtonDown(0)) {
             dragItem = null;
             mouseGridBarDrag = (int)(MouseGridCoords().y);
             mouseGridSlotDrag = (int)(MouseGridCoords().x);
             if ((mouseGridBarDrag < barCnt) && (mouseGridSlotDrag < slotCnt)) { //mouseposition in grid-range
                 dragItem = bars[mouseGridBarDrag].items[mouseGridSlotDrag];
                 if (dragItem == null) return; //only pick up item, not empty slot
             }
         }
         //drop
         if (Input.GetMouseButtonUp(0)) {
             int mouseGridBarDrop = (int)(MouseGridCoords().y);
             int mouseGridSlotDrop = (int)(MouseGridCoords().x);
             if ((mouseGridBarDrop < barCnt) && (mouseGridSlotDrop < slotCnt)) { //mouseposition in grid-range
                 dropItem = bars[mouseGridBarDrop].items[mouseGridSlotDrop];
                 if ((dropItem == null) && dragItem) { //if empty slot and valid dragItem
                     //dropItem = dragItem;
                     //dragItem = null;
                     bars[mouseGridBarDrop].items[mouseGridSlotDrop] = dragItem;
                     bars[mouseGridBarDrag].items[mouseGridSlotDrag] = null;
                     RefreshSlots();
                 }
             }
         }
     }
     
     void RefreshSlots() {
         for (int i = 0; i < barCnt; i++) {
             Bar bar = bars[i];
             for (int j = 0; j < slotCnt; j++) {
                 Item item = bar.items[j];
                 if (item) {
                     bar.cdObjects[j].SetIcon(item.icon);
                     bar.cdObjects[j].SetValueD((item.count).ToString());
                     bar.cdObjects[j].SetTimeValue(item.cdLeft/item.cd);
                 }
             }
         }
     }