I agree that they should absolutely have their own keys. After I left the original home, I kept my keys for 4 months. When it became apparent that WK and the Beast were sticking to one another, I went to the house, picked up a load of my stuff, and left the keys on the kitchen table.

That, however, was not the way that WK and I had decided that I would hand them back. He didn't care that I had keys. He was quite pleased about it, actually, because our youngest had a habit of chronically misplacing his own, and WK knew that if I were available, I could swing by, let the boy borrow my key to get in, and go on my merry way. It was a good system, it worked for ALL of us...except for the Beast, of course! She resented the he11 out of it! Various remarks to the tune of "it's my house, not hers, she has no right, blah blah blah, how do we know she won't come into OUR BEDROOM and do things to MY STUFF", yap yap yap. So, as you may have figured out, I have reasons for thinking that she's behind the "my kids get no keys" action. Sooo annoying.