Do the children have a legal father? Perhaps you can get a written authorization for temporary guardianship from the father or the mother who is in prison. To file a legal guardianship would require a court investigation to approve you as the legal guardian. A voluntary agreement would be preferable and less costly at this time. You would have to check if the Court investigators approved undocumented residents as guardians. legally, I believe they can.
Answered on Jun 22nd, 2015 at 3:38 PM