Barqs and Pepper have settled in with Pibbs. I think they see him as just another guest dog for now, which is probably a good thing. Since we didn't know how well trained he was, we were going to crate him in our bathroom for the first night. He whined a little bit (Barqs laying down outside of his crate and staring at him didn't help) and we eventually took the towels out of the crate and put them at the end of our bed, on the floor, for him to sleep on. He wandered and coughed for a few minutes, but then settled down on the towels. He was still there this morning.
When I got up to let them out this morning, all three jogged and waited for me to get the alarm and open the backdoor. He immediately went outside.
I think we got a really good dog, who just needs to get past some medical hurdles and begin enjoying his new life.