Okay, only other family member is mother's mother, who hates the father, but is not willing to take the boy. She could serve as the trustee or both the father and grandmother can be joint turstees.
Is a guardian ad litem an attorney? Guardian ad litem is something different, and can be an attorney, but doesn't have to be.
Would they pay the father an allowance monthly to take care of the kid? The child would receive death benefits from Social Security which would go to the father. If child support was needed beyond that, the Probate Court and/or Trustee would set a monthly amount.
Would the father have to ask for a certain amount, or submit receipts or what? He would have to ask for a certain amount. Whether he gets it or not is another question. If the amount is reasonable, it's probably going to fly. Child support amounts would be as determined by the guidelines and won't require receipts. Major expenditures would.
Father was estranged from both mom and son, has not seen the boy since he was an infant. Father was in prison but has cleaned up his act and is willing to take the kid. No other relatives. Yeah, father would become custodian. He would not be appointed trustee because of the prison.
So when is there a social security benefit? Yes, as long as mom paid into social security. It takes a couple of months to get going.
Boy is twelve, isn't that too young to be an emancipated minor? New Hampshire has no provisions for emancipation, nor do many states. But twelve is way below the limit. However, if the boy is completely rejecting the father, there are options for custody.