Change your contract ASAP and have mom sign it. She doesn't want to sign, find more families. You have to remember that you're the boss in this business, and people shouldn't be walking all over you.

I have it in my contract that if I'm closed, then parents don't pay. But when they take time off, they have to pay me half of the amount they would regularly pay so that they don't loose their spot, and I still somewhat get paid!