(2) If for any month in which an annuity accrues and is payable under this subchapter the annuity to which an individual is entitled under this subchapter (or would have been entitled except for a reduction pursuant to a joint and survivor election), together with the annuity, if any, of the spouse and divorced wife of such individual, is less than the total amount, or the additional amount, which would have been payable to all persons for such month under the Social Security Act [ 42 U.S.C. 301 et seq.] if such individual’s service as an employee after December 31, 1936 , were included in the term “employment” as defined in that Act, the annuities of the individual and spouse shall be increased proportionately to such total amount, or such additional amount: Provided, however, That if an annuity accrues to an individual or a spouse for a part of a month, the amount payable for such part of a month under this subdivision shall be one-thirtieth of the amount payable under this subdivision for an entire month, multiplied by the number of days in such part of a month. For purposes of this subdivision, (i) persons not entitled to an annuity under section 231a of this title shall not be included in the computation under this subdivision except a spouse who could qualify for an annuity under section 231a(c) of this title if the individual from whom the spouse’s annuity under this subchapter would derive had attained age 60 or 62, as the case may be, and such individual’s children who meet the definition as such contained in section 216(e) of the Social Security Act [ 42 U.S.C. 416(e) ]; (ii) after an annuity has been certified for payment and this subdivision was inapplicable after allowing for any waiting period under section 223(c)(2) of the Social Security Act [ 42 U.S.C. 423(c)(2) ], and after having considered the inclusion of all persons who were then eligible for inclusion in the computation under this subdivision, or was then applicable but later became inapplicable, any recertification in such annuity under this subdivision shall not take into account persons not entitled to an annuity under section 231a of this title except a spouse who could qualify for an annuity under section 231a(c) of this title when she attains age 60 or 62, as the case may be, if the individual from whom the spouse’s annuity would derive had attained age 60 or 62, as the case may be, and who was married to such individual at the time he applied for his annuity; and (iii) in computing the amount to be paid under this subdivision the only benefits under title II of the Social Security Act [ 42 U.S.C. 401 et seq.] which shall be considered shall be those to which the persons included in the computation are entitled.
45 USC § 231b(f)(2)
None identified, default scope is assumed to be the parent (subchapter IV) of this section.