(2) During holidays times our family will go to their homes and we will stay 15 days there. Is it right to go their homes and have their food because my father is giving zakah to them? Please guide us whether my father is doing right way?
بسم الله الرحمن الرحيم
If the sisters of your father are poor and eligible to receive zakah your father may give them zakah money. If your father has to eat or drink at their homes then there is no harm in it though they cook food with zakah amount, it is lawful for your father and his relatives to eat it. But if the sisters are not eligible for zakah as they have gold, silver, or cash or extra goods (not used in daily life) which are equal to 613 gram silver in price then they cannot take zakah, and if it does not reach equal to said quantity then they are entitled to receive zakah. In view of this rule, you should assess or seek the advice of any local Alim so that it is clear whether your father can give zakah to his sisters or not.
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Allah knows Best!
Darul Uloom Deoband