Legal Question in Insurance Law in California

Laypeople often use the term "legal document" as if it means something. It doesn't.

To have your name legally changed requires a court order. You should just send the insurance company a copy of that order. It might be willing to accept a driver's license instead, but to my knowledge there is no law that says it has to.

Mr. Hoffman is right that there is no such thing as a "legal document," except as a vague general concept of a document that has some legal siginifcance. Heck, your credit card statement is a "legal document" for some purposes. You need to ask the insurance carrier what they will accept.