What is the ruling on using usurious money withdrawn from a bank to buy gifts, and then a brother takes and spends them without knowing their source, and how can one dispose of them lawfully?

Usurious money is impure money that must be disposed of by spending it on a public welfare, such as orphanages and well digging, or by giving it to the poor and needy, whether relatives or not, in the form of a gift or aid. If your brother spends it on the family, there are two scenarios: The first is that you are the one spending or a partner in the expenditure. In this case, you have not disposed of it and it must be given out again. The second is that you are not the one spending, and if they are poor and took the money out of their need, then you have disposed of it and are not required to give it out again.