Commish advice needed - switching to keepers.

This is the league's 7th year, and we decided to introduce a keeper format.

I have already determined we will follow the 3 round keeper penalty (e.g. a 10th round pick this year can be kept next year in exchange for a 7th round pick).

My question is, what is the best way to handle players that are not drafted? What problems may arise with players who are drafted and cut by a team, only to be picked up by someone else? Should they be allowed to keep the player at the original draft position?

Fantasy commishes of Reddit, please weigh in with your thoughts on what has worked and what hasn't.

Hopefully this gives you something to talk about in this slow time of the off-season.