Legal Question in Family Law in California

The only person who has legal rights as to the child is the biological mother. Unless she was stripped of parental rights entirely, not just lost custody, she has legal parental rights to the child. If she lost rights entirely, or has no interest in asserting the rights, everyone else who might want custody starts on an equal footing with no actual rights. The only rights children's services and the courts care about at that point is the child's rights. They can order any custody arrangement they find is "in the best interests of the minor child." If there are competing applications for custody or guardianship, that's the standard the court will apply. There is a whole lot of law on what the court can, must, and cannot consider in deciding what is "in the best interests of the minor child," far too much to go into here. If you want to pursue guardianship, the first thing to do is get a child dependency case opened in the county where the child currently resides.