Drag and drop to a specific panel

Hi, I am using the sample scripts of Unity to drag and drop into a panel but I want to add the following functionality: I cannot drag and drop to just any panel but to only a specific one. How can I do that? This is the Drop code:

 public void OnEnable ()
 {
     if (containerImage != null)
         normalColor = containerImage.color;
 }
 
 public void OnDrop(PointerEventData data)
 {
     containerImage.color = normalColor;
     
     if (receivingImage == null)
         return;
     
     Sprite dropSprite = GetDropSprite (data);
     if (dropSprite != null)
         receivingImage.overrideSprite = dropSprite;
 }

 public void OnPointerEnter(PointerEventData data)
 {
     if (containerImage == null)
         return;
     
     Sprite dropSprite = GetDropSprite (data);
     if (dropSprite != null)
         containerImage.color = highlightColor;
 }

 public void OnPointerExit(PointerEventData data)
 {
     if (containerImage == null)
         return;
     
     containerImage.color = normalColor;
 }
 
 private Sprite GetDropSprite(PointerEventData data)
 {
     var originalObj = data.pointerDrag;
     if (originalObj == null)
         return null;
     
     var dragMe = originalObj.GetComponent<DragMe>();
     if (dragMe == null)
         return null;
     
     var srcImage = originalObj.GetComponent<Image>();
     if (srcImage == null)
         return null;
     
     return srcImage.sprite;
 }

}

and this is the drag code:

 public void OnBeginDrag(PointerEventData eventData)
 {
     var canvas = FindInParents<Canvas>(gameObject);
     if (canvas == null)
         return;

     // We have clicked something that can be dragged.
     // What we want to do is create an icon for this.
     m_DraggingIcons[eventData.pointerId] = new GameObject("icon");

     m_DraggingIcons[eventData.pointerId].transform.SetParent (canvas.transform, false);
     m_DraggingIcons[eventData.pointerId].transform.SetAsLastSibling();
     
     var image = m_DraggingIcons[eventData.pointerId].AddComponent<Image>();
     // The icon will be under the cursor.
     // We want it to be ignored by the event system.
     var group = m_DraggingIcons[eventData.pointerId].AddComponent<CanvasGroup>();
     group.blocksRaycasts = false;

     image.sprite = GetComponent<Image>().sprite;
     image.SetNativeSize();
     
     if (dragOnSurfaces)
         m_DraggingPlanes[eventData.pointerId] = transform as RectTransform;
     else
         m_DraggingPlanes[eventData.pointerId]  = canvas.transform as RectTransform;
     
     SetDraggedPosition(eventData);
 }

 public void OnDrag(PointerEventData eventData)
 {
     if (m_DraggingIcons[eventData.pointerId] != null)
         SetDraggedPosition(eventData);
 }

 private void SetDraggedPosition(PointerEventData eventData)
 {
     if (dragOnSurfaces && eventData.pointerEnter != null && eventData.pointerEnter.transform as RectTransform != null)
         m_DraggingPlanes[eventData.pointerId] = eventData.pointerEnter.transform as RectTransform;
     
     var rt = m_DraggingIcons[eventData.pointerId].GetComponent<RectTransform>();
     Vector3 globalMousePos;
     if (RectTransformUtility.ScreenPointToWorldPointInRectangle(m_DraggingPlanes[eventData.pointerId], eventData.position, eventData.pressEventCamera, out globalMousePos))
     {
         rt.position = globalMousePos;
         rt.rotation = m_DraggingPlanes[eventData.pointerId].rotation;
     }
 }

 public void OnEndDrag(PointerEventData eventData)
 {
     if (m_DraggingIcons[eventData.pointerId] != null)
         Destroy(m_DraggingIcons[eventData.pointerId]);

     m_DraggingIcons[eventData.pointerId] = null;
 }

 static public T FindInParents<T>(GameObject go) where T : Component
 {
     if (go == null) return null;
     var comp = go.GetComponent<T>();

     if (comp != null)
         return comp;
     
     var t = go.transform.parent;
     while (t != null && comp == null)
     {
         comp = t.gameObject.GetComponent<T>();
         t = t.parent;
     }
     return comp;
 }

}