I think the problem has nothing to do with families. "Physics disable collisions" action affects all instances of this object, you can not disable it just for one.
I suggest you disable Physics behavior for the dragged block, and re-enable it on drop.
By the way, you should avoid mixing Physics with other behaviors - Pin, BoundToLayout etc. It may cause all kinds of bugs. So this is another reason why you should disable Physics while dragging the block. And when it's dropped, make it immovable instead of pinning.