If the account is to be paid to the child or children, or to descendants of deceased children by representation, as provided in § 1651.2(a)(3), the following rules apply:

(a) Child. A child includes a natural or adopted child of the deceased participant.

(b) Descendants of deceased children. “By representation” means that, if a child of the participant dies before the participant, all descendants of the deceased child at the same level will equally divide the deceased child's share of the participant's account.

(c) Adoption by another. A natural child of a TSP participant who has been adopted by someone other than the participant during the participant's lifetime will not be considered the child of the participant, unless the adopting parent is the spouse of the TSP participant.

(d) Parentage disputes. If the identity of the father or mother of a child is in dispute or otherwise unclear (e.g., only one parent is listed on a birth certificate), the purported child must submit to the TSP record keeper either:

(1) A court order or other administrative finding establishing parentage; or

(2) Documentation sufficient for establishing parentage under the law of the state in which the participant was domiciled at the time of death.