Mollie, I think what Logan said is too true. Whenever we bring another permanent attachment home, we introduce them slowly, one at a time, in the back yard with both of us there and pay attention to both of them to reassure them both that they're not going anywhere. I would suggest taking Buddy bye bye somewhere where it's just the 2 of you and get him some Dairy Queen (that's what our vet always says to the dogs after they get their shots) and just spend time with him. Also, make sure you establish yourself as Alpha NOT Abby. Once both of them understand that YOU'RE in charge and not either one of them, it should be fine. Mike and I have discovered that if we show that we accept the newcomer, then the other dogs just shrug their shoulders and figure that it's just one more!!! lol

Good luck and let us know how it goes.