No chargesheet yet

Kindly mention the "Section of Law" which is registered by police against your brother.

Generally 90 days to file chargesheet.  Do not pay any amounts if they do not accept for mutual consent divorce.  If they do not come forward for mutual consent divorce. tell them you will pay the amount only in Family court at the time of issue of decree of divorce by Family court as per the orders of Family court.  Even in mutual consent divorce deposit the amounts only to court not directly to them during first motion.

I say this to you because, many times police do not file FIR and simply fool the accused party saying we have filed FIR and going to file chargesheet.  If FIR is filed, it shall reach its logical conclusion either by discharge/acquittal of the accused or quashing by HC.  There is no process of "withdrawal by complainant".  If police say, they will withdraw FIR you pay so much amount, never trust and give any amounts to the complainants. If they want any amounts from you let them recover through due process of law, by invoking rights available to them under appropriate sections in various laws like Sec.25 in HMA or Sec.22 in DV Act etc.