Is it permissible to give bank interest to an orphaned fiancée who is experiencing difficult financial circumstances, without informing her of the source of the money?

It is forbidden to acquire, finance, benefit from, or use the profits of usurious banks for personal gain. One must dispose of them immediately by giving them to the poor and the needy. There is no harm in giving some of it to a poor orphan girl, as she is among those who qualify for public funds due to her poverty. However, this charity cannot be considered sufficient in place of the customary gifts that should be given to a fiancée.