[LordKano]

1. Survivor benefits: If someone is in a >2 person marriage, does that mean all of their spouses can continue to collect survivor benefits until the last person dies?

Survivor benefits continue as long as there is a surviving spouse. It doesn't matter if there are 1 or 3.

2. Tax-free inheritance: Similar to the above, but does a >2 person marriage mean everyone gets tax free inheritance?

Every surviving participant in the marriage inherits tax free. Just like now.

3. Healthcare benefits: Could you put 5 spouses on one employee-sponsored health plan?

Yes.

4. Tax laws: Tax laws would need a total rewrite because all brackets/amounts just support a single person or a 2-person marriage.

Married or Single are the current choices. That wouldn't be any different. It would actually incentivize multiple person marriage.

[adevine]

And your answers are fundamentally why >2 person marriage isn't coming anytime soon. All of these solutions are basically break the entire slew of existing financial setups around marriage. Do you think a company would be willing to put 5 married people on the same spousal health plan? Do you think Social Security is going to be OK with 1 person's benefits potentially outliving them for decades as they carry on to multiple spouses?

>2 person marriage is fundamentally different from existing marriage laws in a way gay marriage is not.