As I said before, I have no problems with consenting adults (I'd prefer at least of age 25) being in polyamorous situations, assuming they are mature enough to protect themselves with power of attorney, child custody agreements, etc...BUT - it's a lot harder to change our laws to include multiple partner marriages than it is to change the marriage definition from "man and woman" to "two people", which is why I personally have no desire to pursue that battle.
What happens to work health benefits? to social security benefits? pensions? etc.
I personally have no desire to fight the battle to get polyamorous relationships recognized; I think there are too few of them to worry about it; but if others want to I cheer them on.
BUT BUT BUT - any kind of relationship that involves marrying young girls to old men, driving off young men, not educating girls/women, having the "extra" spouses and children get welfare - THAT I am totally opposed to. (yes, people fall on hard times and need welfare; but if you are marrying multiple people and promising to support them - you should be able to do so). How we balance it all out legally will be very tough. But as I said before (apologize for repetition) maybe if we bring this relationships into the sun, at least we can be sure kids are educated appropriately as to their options.
I think it's the Mennonites (I could be wrong) who send their young adults out into the non-Mennonite world for a period of time, so they can see which world they prefer. I wish the fracking fundamentalist polygamists would do the same.