I have a 9 yr old fixed female Russian Blue. I also have a 9 yr old fixed male. They have been together since they were kittens. There is no doubt the female is dominate. The issue is she marks only my things or my daughters. Any thing of ours that is on the floor is fair game. She does not urinate on the carpet, rugs, or tile. She never marks my husbands things. I have tried several boxes in different rooms and different types of litter. She does not seem to have an issue with the boxes. I think she is just letting me know she is the boss. Any suggestions?