We have two cats and one of them has issues with using the trays for poo (she will wee in them though). She either poos next to the trays or by the front door (a local Tom cat sprays our door so I think that's why she does that there).
Anyway, we have three trays. Two in the upstairs bathroom and one in the downstairs bathroom. We've spoken to a behaviourist about the poo issues who said the current advice is to have two litter trays for each cat and they all need to be in different locations. I'm struggling to think of four places to put the trays. So where do you have your trays?