Sorry, I haven't worked with the drag and drop behavior that much and I think my advice was unhelpful as a result as there are no dragdrop "events" necessary to initiate the dragging.
I think families are your best bet. You shouldn't need to create more than one unless the objects you're draggign/dropping aren't all sprites as the family should be able to be all inclusive I think. I'm not sure how behavior triggers and actions work with families because I can't make an example capx with the free version of Construct. But when you want to disable the behavior you should try adding a "family is on layer X" condition with a dragdrop "family - set dragdrop disabled" action.
Again, sorry I started off on the wrong track, if I could help you more with families I would.