2Regulations may provide for treating benefit paid to one person in respect of another as being a child of the family, or the wife or husband, or an adult dependant, of the first-mentioned person as having been properly paid for any period notwithstanding that under regulations relating to overlapping benefits it is not payable for that period by reason of a subsequent decision either—
(a)that the said other person is himself entitled to benefit for that period ; or
(b)that a third person is entitled to benefit for that period in respect of the said other person in priority to the first-mentioned person,
and for reducing or withholding accordingly any arrears payable for that period by virtue of the subsequent decision.