Some tips:
only 2 cats per tray. change it every day. you need 2 trays ofr 3 cats.
Don't change litter. This can upset cats. I changed mine when I had a
dozen or so cats. poop all over the place.
Toileting somewhere else is often a sign of illness or the cat is upset
about something. I bet it is the litter change in this case.
What is more gross is stepping in cold cat puke, usually with a big fur
ball in it, when you get up in the moring, or finding one on your
pillow!
Or skid marks evry where when they try to get a clinker off.
The dogs do that too and yes they ahev long hair. If John is here I
usaully get him to hold them so I can comb it our of their bums. He is
such wimp-complains about the smell all the time.
bw
colin