Good luck with Oliver. He may never be "lovey dovey"' with his siblings but as long as he can co-exist with them and he's loving and affectionate with you , you're fine. I've had cats (littermates even ) who just barely tolerated each other for about 15 years . Till the day one passed on and then the other was very upset for months. Go figure. What is this Feliway diffuser? Is more effective than the spray ? I may have need of it in a few weeks when my parents move back up north again. They have spoiled and pampered my kitties and we work such long hours..I'm afraid they are going to have a difficult time adjusting to the change.