Is it permissible to dispose of money acquired from interest-based bank profits and spend it on needy relatives such as an unemployed brother, a niece preparing for her marriage, and a married sister whose husband cannot provide her clothing? And what should I do if this action is not permissible by Islamic law?

It is impermissible to engage in usurious transactions with banks or other entities. A Muslim must abandon it and repent from it. Usurious gains are to be spent on the welfare of Muslims and the needs of the poor. It is permissible to give them to needy relatives or family members with the intention of divesting oneself of them. What has already been spent from these gains does not require a replacement, but repentance and seeking forgiveness are obligatory.