We have two 5 year old cats (littermates) and our puppy Shelby (now 17 weeks). We had a third cat who was put down a few months before Shelby arrived and since then the male cat (Tramp) has been walking around like he lost his best friend (which he did I guess ) He so wants to be friends with Shelby but just won't give in!!! The female cat (Lady) wants nothing to do with the dog and we totally expected that, but Tramp is so interested in Shelby, and vice versa, but they just won't give in to each other. LOL. Tramp was sitting on the back of the couch last night, Shelby was jumping up at her and Tramp just kept popping her on the top of her head with his front paw. I guess they might have been playing, but Tramp did not look amused. I keep waiting to walk into the kitchen one time and find them curled up on Shelby's pillow together and being like, "Well, it's about time!!"
I hope your critters can make peace and start living in harmony.