I think all that gets treated by automatic operation of law. They have established rules and procedures. And if you live in a community property state, anything one spouse inherits after the marriage is automatically shared by the other spouse.
I was told that if the money was not commingled, it was not community property. We have decided to leave the issue of comingling up to the kids. They can do it or not depending on their wishes.
Actually, this not is accurate, at least as far as California (no fault state) is concerned. I think you have to be married/common law married for 10 years for the inherentance to one party to become automatically community property of both parties. I know this because my father's passing is what precipitated my first wife's divorce filing. She guessed wrong on what was really a tiny amount of money. Now she says I was the only person she's ever loved. Yea, right. I think she is currently going through divorce number 3.