What I did was use diff bedding in their litter boxes then if I did find a spot where they went I soaked it up with the litter bedding and cleaned the spot with nature's miracle. I do have litter boxes on almost every level.(placed where they were going the most ) my girls caught on quickly and as the new ones come in they seem to follow suit!
Goodluck and stay patient!
I will have to get a few more litter boxes! I am using towels in my FN so I cant really see where they are peeing. I do have natures miracle so I will clean my trays with that tomorrow and get another potty or two for them! Thanks.. cindy