UI Drag/Drop: Removing items from original container when dropped into another container

UI Drag/Drop: Removing items from original container when dropped into another container


Hello
 
I am working on a complex user interface where users can draw meal tables and can drag/drop guests onto seats from the guests list, and also from one seat to another seat of the same table or another table etc etc. I want to remove the guest from guest list when it is dropped on some seat. Similarly, it should be removed from the original seat when it is dragged to some other seat. I am using droppable's drop event to place the guest and remove it from original container.
 
Now the problem is (I think):
I am trying to remove the original source(draggable) of a drag/drop event before completion of the event, and it is generating error.
 
How can I achieve the desired result? Simply speaking, I want to move an item from one container to another. I would appreciate any help. Thank you in advance ;)
 
Khalid