Legal Question in Real Estate Law in California

The result in probate required more than just lack of your grandparents being married. It also had something to do, presumably, with how he, or they held title to the property.

Marriage raises a rebuttable presumption that the property is held as community property. If a couple is unmarried, the property may be his property solely, her property solely, or they may own in jointly, either as tenants in common or as joint tenants. So, four possibilities (at least).

Hopefully, the probate process sorted out the ownership issues correctly, and the son was truly entitled to inherit. This would be a correct result if he died without a will, or if he had a will or trust, the will or trust directed such an outcome.

Now, let's turn to your question about a form. What are you trying to accomplish? As I read your facts, you are not an owner, part owner, former owner, contractor, tenant or otherwise responsible for this property. Why do you need a form? Who would sign it, and who would be the party to be released or held harmless? A person who inherits a property gets it as a gift, "with all faults."

Now, what about grandma? Was or is this property her home? What does the "stepson in common law" intend to do about her? Maybe she is to have a life estate in the property, in which case some kind of a release or other agreement about maintenance of the property during her lifetime might be appropriate, but this would have to be written up by a lawyer who can interview them and see the property, and is highly unsuitable subject matter for a form.