Boy, you've got a dilemma there. Everything I was going to suggest, you've already tried. All my cats sleep in the basement; all their beds, food, toys, litter boxes, etc. are there and it's like they have their own apartment. I don't allow them upstairs at night because then they want to play and make noise and I need my rest. If there's no way you can put them in a different part of the house, can you cage them at night in a really large cage w/food, water and litter pan?