Is it permissible to give zakat to a sister who is about to get married, knowing that her father has passed away, there is no judicial ruling for her maintenance, and she lives with the zakat payer and his mother, and some of her brothers provide for her?

A woman's marriage expenses are obligatory upon herself if she has wealth; otherwise, they are obligatory upon whoever is responsible for her maintenance. If the mother is wealthy, the expenses for her daughter are obligatory upon her, and the mother may give her daughter from the zakat if she is in need. However, if the mother is poor, the expenses become obligatory upon the able brothers, provided that the brother is wealthy and the sister is poor and an heir to him, as stated by Ibn Qudamah: "Three conditions are required for the obligation of maintenance: that they are poor, that the one upon whom maintenance is obligatory has wealth to spend on them in excess of his own needs, and that the maintainer is an heir." In the event that the sister's maintenance is obligatory upon the brothers, it is not permissible to give her from zakat unless she is in debt.