Legalizing Polygyny: What Would It Take?

Families that follow the Islamic religion, the Mormon religion, and other religious sects that permit men to marry more than one wife could argue that polygyny is a constitutional right guaranteed by the first amendment. But currently it is illegal. What would it take to legalize polygyny? Would families that practice polygyny be willing to file a Federal lawsuit to demand the rights of all wives to be legally recognized? How would women insure all wives in a polygynous family received their share of the social security benefits, pension money, and property left behind after the passing of the husband? How would women uphold each other's rights to be publicly respected as wives?