I think bringing in a puppy instead of like an adult dog would be a lot easier for them to get used to. I have 5 dogs and they all get along surprisingly well. Shadow was an only dog for 7 years and we were afraid adding another dog but she adjusted great to Micki and Mini, no problems at all. I have 2 males in the house, and I've gotta say that I actually have more problems with the 3 females getting along, the boys are usually great together.

We defianately need some pictures of Face and Senorita, its been waaaay too long And the puppy too
Good luck!!