Whether or not chi's get along is a complicated thing. LOL
We've had Jaelyn since last summer. She was our only adopted chi until a few weeks ago, but we foster chi's alot of the time. So there's usually an extra chi in the house. Occasionally there's another small breed dog instead. Jaelyn didn't get along with the girl chi's. She'd bite them on the tummy and bark at them. The energetic boy chi's we've gotten she barks at more and can be aggressive towards them.
Bring into the mix our new three year old male chi and she pays him no attention whatsoever. It doesn't help that if I'm not holding him he hides under my chair. He's very submissive. (Just what she needs.)
I think she's aggressive with our foster chi, Oliver, because he's very high energy and he gets her worked up. I think (and seriously hope) when he's adopted that she will go back to her semi-layed back personality since the only chi presence in the house will be Jaeran. (We need a serious break after Oliver gets adopted. LOL Plus we need to give Jaeran time to settle into the house and he can't do that with Oliver around.)
Whether or not chi's get along seems like a science. I will say this... if you both get two laid back/submissive chi's (not high energy) there is a much better chance of them getting along. Or if one of you gets a high energy/dominant chi try getting a submissive chi as your second one. If you get two high energy/dominant chi's chances are your house will be chaos. (Just like ours. LOL)
Just a thought, but if you're adopting puppies or young adults from the same litter there is a bigger chance of them getting along already.
I hope this helps you at least a little.