Yes, if the relative/friend is poor or needy, you may give him/her the interest money.
No, you do not need to inform them of the source of the money and you should not, so you can be sensitive to their feelings.
We rely on our generous community to create a lasting impact and ensure the continuous operations of your Masjid as the gathering place, school, and house of worship for Muslims across the Triangle.
Those who spend their wealth in charity day and night, secretly and openly—their reward is with their Lord, and there will be no fear for them, nor will they grieve.”
– The Holy Quran 2:274