Is it permissible to give the profits from currency exchange and bank interest to the orphaned children of a deceased brother, or to pay off the debts of another brother? If not permissible, what is the permissible way to spend these funds, and where would it be best to spend them?

If the profits resulted from forbidden transactions and usurious interest, one must repent and dispose of them by spending them on charitable causes. There is no harm in spending them on relatives who are not legally dependent if they are in need. However, if the profits did not result from forbidden transactions, then they are lawful.