31 C.F.R. § 360.63 – Payment to a parent or other person on behalf of a minor.

(a) If the owner of a savings bond is a minor and the form of registration does not indicate that there is a representative of his or her estate, and if the minor is not of sufficient competency to sign the request for payment and to understand the nature of the transaction, payment will be made to either parent with whom the minor resides or to whom legal custody has been granted. If the minor does not reside with either parent, payment will be made to the person who furnishes the chief support for the minor.
(b) The request must appear on the back of the bond in one of the following forms:
1. (1) Request by parent:
  I certify that I am the mother of John C. Jones (with whom he resides) (to whom legal custody has been granted). He is __ years of age and is not of sufficient understanding to make this request. Mary Jones on behalf of John C. Jones
2. (2) Request by other person:
  I certify that John C. Jones does not reside with either parent and that I furnish his chief support. He is __ years of age and is not of sufficient understanding to make this request. Alice Brown, grandmother, on behalf of John C. Jones