بسم الله الرحمن الرحيم
(Fatwa: 1445/994/L=11/1434)
The abovementioned details indicate that the fault lies neither with your brother nor with your family; therefore filing FIR against your family is zulm (oppression) which is not allowed in Shariah.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband
