I would make them stay in their beds until naptime is finished. Whether they cry the entire time or sleep, is up to them. I would check on them every so often to make sure they have not pooped, vomited, etc, but try to do it discretely so they don't know you are there. It takes time...some kids are really stubborn, but if you never give in, they will learn and you will have your quiet time back. Plus, they need the sleep just as much as you need your break...it is for their own good as well. Good luck!