If your parent is alive, get adopted, no matter how old you are.
If your parent is dead, you may be able to revise your birth certificate. You will need to get a court order to change your name and have your birth certificate changed. We had to figure this out on our own, none of our lawyers were smart enough to figure this out. By the time we realized it, it was the day before we were supposed to submit “the agreement”. We were all so tired of all the legal battles, we just signed the agreement (under duress).
This would have put us at the same standing as Miss Adopted Middle Aged Woman as far as being a legal heir. Hopefully, this information helps someone else who might be shortchanged by the legal system.