Any person to whom United States Government life insurance shall be payable may assign such person’s interest in such insurance to the spouse, child, grandchild, parent, brother, sister, uncle, aunt, nephew, niece, brother-in-law, or sister-in-law of the insured. Insofar as applicable, the definitions contained in section 3 of the World War Veterans’ Act, 1924, in effect on December 31, 1958, shall apply to this section.