We'd have to discuss what to do with the prospects that are dropped mid draft. I figure they should go back into the pool and be able to be drafted that same draft.
You'd also have to make this move/announcement before your turn comes up. Don't want to have people using their whole window to try to decide if they wanna drop a prospect for another one. So as soon as the pick comes up, if you don't have an empty spot, the pick would disappear.