A brother may give his zakah money to his brother and sister, his zakah shall be paid with two conditions: (1) The brother and sister are poor and are entitled to receive zakah and do not belong to a Sayyid family. (2) The zakah amount is given in their complete possession that they may use it as per their choice. It shall be necessary to make the intention of zakah while giving the money. This intention is not enough that whatever I am spending it is zakah and if at the time of giving the intention of zakah is not in mind then zakah shall not be paid.
Allah knows Best!
Darul Uloom Deoband