I'm glad to hear that things are starting to improve. When I tried the Cat Attract Litter, I just put some of it on top of the old litter that I was using. I also had to add 3 more litter boxes. Now I use Dr. Elsey's Precious Cat Litter For Muliple Cats and I only occasionally buy the Cat Attract Litter to put on top of it.

Most of my cats also prefer not to have covers on their litter boxes so now I only have 2 with covers. Sometimes they will spray over them but not as often as on the ones with the covers. I've been putting the puppy training pads under the litter boxes and also in the back of them so that if they do spray over it will catch most of the pee. So far this has been working well for me. Maybe you could also tape some puppy training pads to the wall in back of the litter boxes. Good luck.