New Kitty Using Resident Kitty's Litter Box!!!

My new and resident kitty have been integrated for 1 week. I have resident kitty's litter box in a half bath and I've been looking forward to the day when BOTH litter boxes are in the same room...much easier for me scent-wise.

Anyway, each day I moved new kitty's box a little bit closer to the half bath...little bit closer...and finally, today, it came to rest in the hallway just outside of the half bath. I thought, "This is it!!! Tomorrow they will be able to be in the same room!" As I was leaving this morning, I saw resident kitty jump into new kitty's litter box and use it!!!!

Resident kitty has a 'special' litter box with extra-tall sides because he sprays. I do NOT want him using new kitty's regular-sized litter box for this reason. Also, I don't want the new kitty to be freaked out by another smell in his box and stop using it. What should I do??

Bijou and Mika each have their own box but they both use each other's box. Both are covered boxes.

I don't think you are going to have much luck making them only use their own litter so I would suggest you get a covered or higher box for your new kitten as well (if the sides aren't too high for the kitten to get in easily) and then if the resident cat uses that litter he won't spray all over.

Rosie and Sophie use each others as well, and normally Sophie goes on after Rosie's been on to cover up where she's missed

I'm having the same prob...Jovi is using Cody's box and she hates it!! I think that's why she started peeing in the house. I'm trying to keep a better watch on when she needs to go in it because he follows her everywhere!!

Mine share both litter boxes, sometimes one right after the other. I always read on here it should be 1 box for each cat plus 1 more. I don't have the space for a 3rd box, but if you do maybe try that. Do you have room for a 3rd box?