If there are current court orders, then his sister will need to petition the court to modify those orders to make her the sole managing conservator of the children. Your boyfriend cannot "sign his custody over" but he and the mother will need to consent to the modification suit. Please note that his sister could, if she becomes the legal conservator of the child, eventually petition the court to terminate both parents' parental rights because it sounds like neither parentis going to be available to the child for a period of two years or more because of incarceration. That is grounds for termination of parental rights
Answered on Feb 25th, 2019 at 9:08 AM