As-salāmu ʿalaykum Shaykh, a young man used to take money (10–20 dollars each time) from his younger brother for years until he lost track of the total. He now regrets it but cannot return all. He asks: can he agree with his brother on a set amount so his debt is cleared? Barakallāhu fīkum.

Ustadh AbdulAziz al-Haqqan
Sure he can pay him back whatever makes their hearts at ease and also not cause hardship for any of them.