We have just moved house and some of my cats have been peeing and pooing on the carpet and in the bathroom, I have put a dirt box in the wash house and showed everyone but still some of them persist.

You can try spraying down vinegar after you clean up the messes. It gets rid of the smell and might convince them that they need to use the litter box.

Change is always a hard thing to adjust to.

Keep showing them where they need to go. Eventually they'll relax and start to go where they need to. Be persistent and always show them where they need to go. You might want to control water and food intake for better house training results.

Good Luck.