All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.
The question is not clear. In general, what the brother earns from his work belongs to him alone. However, if he works in a company or shop that is owned by the whole family, then the determining factor in this regard is the contract between him and the family: did he volunteer to work on their behalf without a salary, or is he working for a salary, or is he a partner? If there is no contract between them, then the determining factor is the common practice in their community. If he volunteered to work without a salary, then the business is not his. If he is a partner, he is entitled to his agreed-upon share. If he is working in return for a salary, then he is entitled to his agreed-upon salary.
Allah knows best.