I watch 2 shih tzus for a week, every month or so, when their mommy goes out of town. My Jimi loves going over to see them! Jimi is still a puppy, so he is much more energetic than these dogs. He jumps all over them, trying to play, (fun to watch) but they don't have any of it. By the end of the week, I think the shih tzus are just sick of Jimi and can't wait to get him out of the house! lol.
When you first introduce them, make sure they get along okay. At first, the other dogs loved Jimi but as time went on they showed aggression towards him. I think they felt threatened and were thinking, "Oh no! What is this cute new puppy doing in OUR house?! I hope he doesn't think he is going to live here!" lol
When he was younger and did not go up and down the stairs, I would just block the stairs off with a gate. He eventually learned how to go up stairs first, but he would cry when he wanted to go back down the stairs because he didn't know how to go down and was scared.
For now, I would just baby-gate the stairs off. It makes things alot easier!
Also be careful about where you place their food bowls. They might try to eat each other's food (which can cause food aggression and also tummy aches!), but if they eat the same food, that is great- You dont really have to worry about it as much, although they may still prefer to have separate eating places. (You mentioned they are used to crates, so maybe they could eat in there.) I know one of the shih tzus kept trying to eat Jimi's food, so I had to gate Jimi off when he ate.
Hope this helps!
Oh, and I agree with everyone else. You will want to get another.
