Is it permissible for a working sister to purchase the sacrificial animal (Uḍḥiya) if the brother is the provider for the household and not the father, and will she be rewarded for that?

The conditions for the permissibility of sharing in the sacrifice (Udhiyah) are that the sacrificer (Mudahi) must be the one who financially supports those he wishes to include. This is the view of the Maliki school and a position within the Shafi'i school, which some have authenticated. According to this view, a single sheep suffices for the sacrificer and his household (those he financially supports). They cited the Hadith of Abu Ayyub: "We used to sacrifice one sheep, which a man would slaughter for himself and his household."

Therefore, if the aforementioned lady fully supports the household and they live with her in one house, a single sheep for the sacrifice suffices for all of them according to the Malikis and what some Shafi'is have authenticated. However, the preponderant view among the majority of Shafi'is is that it is sufficient in such a case.