20 CFR §222.30

1. (a)Determinations will be made regarding a person's relationship as the child of the employee and that person's dependency on the employee (see subpart F of this part) when—
   1. (1)The wife or husband of an employee applies for a spouse's annuity based on having the employee's child in care; or
   2. (2)The employee's annuity can be increased under the social security overall minimum provision based on the child; or
   3. (3)The employee dies and the claimant applies for a child's annuity.
2. (b)A determination will be made regarding a claimant's relationship as the child of the employee when the claimant applies for a share of a lump-sum payment as a child.