Is it permissible for a husband to give his wife—with whom he has not yet consummated the marriage—from his Zakat money, and similarly for her brother to give her from his Zakat money, with the intention of helping her impoverished father?

As long as you have entered into a marriage contract with your fiancée, she has become your wife. The ruling regarding paying your zakat to her depends on the preponderant opinions of jurists concerning the reason for the wife's right to maintenance from her husband. The fatwa adopted by us is that maintenance becomes obligatory upon full enabling [of conjugal relations] and is not obligatory merely upon the marriage contract. Therefore, if she has not yet enabled you to be with her, and you are in the period of preparation [for the wedding], her maintenance is not obligatory upon you. In this case, it is permissible for you to pay your zakat to her, provided that she is eligible to receive zakat. If she is eligible to receive zakat, it is permissible for your brother to pay his zakat to her. It is also permissible to pay zakat for wedding expenses and bridal preparations, provided that it does not exceed necessities and extend into luxuries.