I could see it happening with immigrants who got poly-married somewhere else where it was legal

How does this resolve if they accept one person being in two marriages?

@MartinRandall Do you mean rather than having three people who are all considered to be married to each other, there is one person who is married to two different people at the same time, but those two people are not considered to be married to each other?

I would resolve that as YES as long as the state is aware of and accepting that arrangement. So like if a pilot manages to have an east-coast wife and a west-coast wife and they don't know about each other and the states involved don't know about each other, I would resolve that as NO, but if the people are all aware and accepting of it then I would resolve that as YES.

@theincredibleholk I was thinking of that case or the case of the people with three marriages between each pair. Thanks for cleaning it up.