You can't. But you can acquire new ones. You can claim the same rights as a *de facto* parent in a custody proceeding in Family Court. Juvenile Court can step in, make the children "dependents" of the Court, and assign them to "foster care" with you. A guardianship can be created through Probate Court, and your mother probably should be in a conservatorship.
Answered on Aug 18th, 2015 at 9:31 PM