Why not dozens? hundreds? fraternities? extended family groups? corporations?
So if three manses get marrieds together (sic), are they all married to each other or is one of them married to two dudes and the two dudes each only married to one guy?
If the common male dies, are the other two both single? Are the other two permitted to each take a second husband while they are in the marriage with the common guy?
If one guy in the marriage gets a divorce, are the other two still married to each other or would they need to refile their paperwork and renew their vows?
Did one of them regret the decision to marry two other partners when he discovered that bigamy didn’t mean getting bigger?
One city can group marry another city...
You mentioned corporations. That would put a whole new spin on mergers!