Legal Question in Family Law in Massachusetts

Re: do i have to probate legal guardianship

Your nephew's mother does not have the legal authority to appoint a guardian, only the Court can do that. She can allow her son to live with you, but that is not the same thing.

The child's father has rights, and in a contest between a non-parent and a parent, the courts will tend to favor the parent. Where is the child's father??

The document is not going to have much of a legal effect on a Court. It may be enough to convince a school to register him, or to keep you out of trouble if the child's mother claims you kidnapped the child.

I cannot tell what you are trying to do, so I do not know whether this letter achieves the purpose you intend. An attorney could help you sort out what you want to happen, and how to make that happen so that you are not in trouble....

Re: do i have to probate legal guardianship

Yes the Court must sanction this guardianship. If both biological parents consent this is a fairly routine process. However should the child's father object the matter can be quite complex.