1) if police refuse to register an FIR you can file private complaint before magistrate under section 156(3) to direct police to investigate and submit report
2) in the alternative approach senior officers and complain against inspector refusal to register FIR
3) it is true that forgery is serious criminal offence and cannot be with drawn by mere affidavit
4) you should file both civil and criminal case . if you want share in property partition suit is must
5) if FIR is lodged brother can obtain AB