I'm asking for a friend who's second kitten does this and they've tried so many tactics, but nothing is working for them. (Using a second hooded tray for them). The other sibling kitten does theirs fine in their own litter tray without issue. They're now 4 months old. I think they've used Feliaway and something else to no effect. Can someone suggest anything, please? Thanks.
NB. They've both been seen by the vets, been treated etc.