(a) Assignments of all or any part of the beneficiary's interest may be made by a designated beneficiary to a widow, widower, child, father, mother, grandfather, grandmother, brother, or sister of the insured, when the designated contingent beneficiary, if any, joins the beneficiary in the assignment, and if the assignment is delivered to the Secretary before any payments of the insurance shall have been made to the beneficiary. However, an interest in an annuity, when assigned, shall be payable in equal monthly installments in such multiple of twelve as most nearly equals the number of installments certain under such annuity, or in two hundred and forty installments, whichever is the lesser. The provisions of this subsection shall not be applicable to insurance maturing after July 26, 1962.

(b) Except as to insurance granted under the provisions of section 1922(b) of this title, any person to whom insurance maturing after July 26, 1962, is payable may assign all or any portion of such person's interest in such insurance to a widow, widower, child, father, mother, grandfather, grandmother, brother, or sister of the insured when the designated contingent beneficiary, if any, joins the beneficiary in the assignment. Such joinder shall not be required in any case in which the insurance proceeds are payable in a lump sum.