Legally Adopting A Child In Texas

My mother (f54) dated a guy 9 years ago who had an infant daughter. The mother of the girl gave birth to her in prison and is still in prison. The father had my mom take care of the child her whole life. She is almost 10 and only knows my mother as her mother. The girl does not have a birth certificate or any official documents.

The father is a POS, constantly in and out of jail. He and my mom have not been together for years, but she still cares for the girl. If he gets a new girlfriend, he takes her to live with him and his new woman for a few months before it falls apart and she ends up at my mom’s again.

My mother believes there is no legal avenue to become the legal guardian for this child, but I believe she has just become accustomed to the life she has been given.

Unprofessionally, my opinion is that she should just leave the girl with her father and move on with her life, but she truly believes that she is this girl’s mother and can’t just let go.

Is there any way my mom can petition for some sort of custody of this girl? It has caused so much stress in not only my mom’s, but my life for almost a decade.