Legal Question in Elder Law in California

Re: living trust

At the moment your son receives the funds, they are his separate property and don't belong at all to his wife.

However, if your son commingles the funds - e.g., if he deposits them into a shared bank account, or if he spends them on an asset (like a car or a house) that's titled as a community property or joint tenancy asset - then he's likely made a gift of the separate property to his spouse, or otherwise made it effectively impossible to later segregate his separate property from the community property.

It's very common for people to accidentally or unthinkingly convert separate property into community property - it's also very common for them to choose to do so, because they want to share with their spouse, even though others may disagree.