Q. Which is the best way for someone who’s wife asked him to be her Shaliach (agent) and represent her at the Hatarat Nedarim (absolution of oaths and promises ceremony) done on Erev Rosh Hashana. Is it repeated for her? How? Can it be done also for a daughter?
A. Shulchan Aruch (Y.D. 234: 56, Shach ibid. 70) rule that a husband can be an agent for the Hataras Nedarim of his spouse.
Horav Shlomo Miller’s Shlit’a opinion is that the best and easiest way to carry on this agency is for the husband after the end of his personal Hataras Nedarim act, to inform the Dayanim of the Beis Din that he is also representing his wife as a Shaliach of her. He then just proceeds to ask for the absolution of her Nedarim also. The Beis Din will continue
to declare three times “Mutar Lah” or they are now permitted to her. (See similar ruling in Piskei Teshuvos 581: 19: n. 140)
As mentioned by the Poskim quoted, the above applies only to a wife since ‘Ishto Kegufo,’ the wife is one with her husband, and does not apply to a daughter.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit’a