Is it forbidden to eat and dress from the money of one's parents and siblings if their salaries are deposited in usurious banks without interest?

It is not permissible to voluntarily open an account in a usurious bank, nor to keep money in it, as this constitutes aiding in sin. Therefore, you must advise your father and brothers to transfer their salaries to an Islamic bank, and remind them that opening an account in a usurious bank, even without interest, is considered aiding in what is forbidden. As for eating their food and wearing their clothes, there is no harm in that, especially since they do not take interest on their salaries, so their money is not unlawful in this respect. However, the prohibition is related to their aiding the bank in what is forbidden.