She/he does this within hours of the boxes being clean. I clean them a couple times per week.
The problem with feliway in my mind is that the box they use the most is maybe 3 feet from where the unknown culprit keeps pooping. Wouldn't that keep them from using their box?
Thanks for your help!
Nope, the Feliway is like kitty happy drugs (pheromones). The closer it is the more likely it will actually help. I agree with others that stress could be an issue, Feliway will also help with that.
