(vi)
if there be no such widow, widower, child, grandchild, parent, brother, or sister, to the estate of such employee:
Provided, however, That if the employee is survived by a widow, widower, or parent who may upon attaining the age of eligibility be entitled to benefits under this subchapter or under the Social Security Act, such lump sum shall not be paid unless such widow, widower, or parent makes and files with the Board an irrevocable election, in such form as the Board may prescribe, to have such lump sum be paid in lieu of all benefits to which such widow, widower, or parent might otherwise become entitled under this subchapter on the basis of the deceased employee’s compensation and years of service or under the Social Security Act on the basis of the deceased employee’s wages from
(A)
employment with an employer as defined in section
231
(a) of this title or
(B)
service as an employee representative as defined in section
231
(c) of this title. Any election made and filed by a widow, widower, or parent pursuant to this subdivision shall be legally effective according to its terms. After a lump sum with respect to the death of an employee is paid pursuant to an election filed with the Board under the provisions of this subsection, no further benefits shall be paid (other than to a survivor in the circumstances described in paragraph (3)) under this subchapter or the Social Security Act on the basis of such employee’s compensation and service under this subchapter, except that nothing in this subchapter or the Social Security Act shall operate to deprive a widow, widower, or parent making such election of any insurance benefit under title II of the Social Security Act [42 U.S.C. 401 et seq.] to which such individual would have been entitled if the employee had not rendered service as an employee under this subchapter.