Fathers Partner claimed marriage with no certificate

Hello (again), location: California, LA county

So I posted recently about finding out my father passed and I went and got a death certificate to claim funds.

However, I am pretty sure my dad did not marry his partner.

The death certificate was updated via affidavit request that he was married, this was done so by the funeral home. Yet, I called to confirm if his partner provided a certificate of marriage, they said no. They said they usually just sign it if nobody is contesting it.

Now his life insurance policies won’t give out funds to his children because of a spousal rule. I don’t have a time frame on when they could’ve gotten married and I’m 90% sure they didn’t but the vital records won’t look for me when I call but also says they don’t do “random” searches.

I’m confused how I can prove that they weren’t married to have his death certificate updated so his children get his benefits and retirement.

Author: Front_Negotiation559