I wish I knew the answer.... I have one older cat who refuses to use the litter box to poop in. REFUSES!!! I have 6 boxes and 4 kitties in the house as of now. He'll poop next to the box, but not in the box. Even does it when I'm right here staring at him. Loud clapping deters him, but only for a while.

I hope you can find something to help your kitties use the box.

For Odor clean up, I used BAC A ZAP, which is non toxic for cats, but will clean any bio hazard that may come up, and even works on hard wood floors!!! I ordered mine online, just look for BAC A ZAP.