There was no showing that the son, who had reached the age of 21, was likely to become a public charge or that the husband of the infant daughter cannot support her. Nevertheless, the interests of justice require a hearing as to the extent of the modification which should be granted (Kruger v. Kruger, 279 App. Div. 808; cf. Phillips v. Phillips, 1 A D 2d 393, affd. 2 N Y 2d 742). The question as to whether the modification of the award should be retroactive to the return date of the motion rests in the Special Term’s sound discretion to be exercised on the basis of all the facts adduced at the hearing (Harris v. Harris, 259 N. Y. 334; see, e.g., Averett v. Averett, 110 *934Misc. 584, affid. 191 App. Div. 948; Rosenfield v. Rosenfield, 285 App. Div. 817). Beldock, P. J., Kleinfeld, Brennan, Hill and Rabin, JJ., concur.