Is it permissible to give an widowed sister with children usurious bank interest, and is that considered feeding on usury?

It is not permissible to deposit money in a usurious bank except out of necessity or dire need, because it aids them in sin. If a person is compelled to do so, it is preferable to take the interest and dispose of it by spending it on charitable causes. However, depositing money in a usurious bank with the intention of obtaining interest and spending it on charitable causes is absolutely forbidden. Therefore, it is not permissible for you to deposit your money in a usurious bank for the purpose of spending on your widowed sister and her children. You must invest your money in a lawful manner and spend on them from lawful earnings.