Currently, I’m polite to friendly with all of them. No outstanding conflicts. It’s sometimes literal kitchen table poly with one, and the others I only see at like parties and such.
Some years ago I had two partners that absolutely did not get along with each other, and that was rough. Recently I was able to do a dinner with 3 partners and everyone had a good time.
I try not to make a big deal about folks meeting. I try to model after meeting your friend’s friends.
I start with the thought that my metamors, as a subset of all people, have already been vetted by people that I love and care about. Starting with that assumption tends to make things go easier. At least that’s been my experience.