I'm not even against polygamy in principle...or polyandry, or other complex forms. But the rules for it would need to be VERY careful, and there would need to be notarized, witnessed agreements by all parties stating that they are aware and cognizant of all the terms.

No more 'pressure' setups by obscure sects with underage girls being the focus...

Yes, I could write up the rules, but nawwww...I won't bother, because I think it's HIGHLY unlikely to ever be legal.