How do I Create Drag And Drop Path?

I'm making a drag & drop style puzzle game. For an introductory level I want the player to have to drag path pieces onto a body of water in order to cross it. the problem is I'm not really sure how to do it.

issues will be drag n drop will pick up and move all over the place.

one way to limit is if object is not overlapping pathsprite = drop

another way would be on drag n drop clamp x,y so it one moves in straight line to target.