Procedure for Sale of property

I am selling my flat. Chain of agreements Agreement between builder and buyer dated 26 Nov 82 True copy available, index II available Original Sales deed between first buyer and second buyer dated 15 Jul 85 on Rs.5 stamp paper. Not registered. Understand registration requirement came up wef Dec85. Original share certificate in the name of the buyer available Flat sold to me on 5th May 2005. Agreement registered, available. Share certificate transferred to my name. Agreement made with buyer oct 2016, registered and stamp duty paid. Bank where buyer has applied for loan have asked for police complaint to be lodged for missing first agreement with builder, issue public notice, seller and buyer to sign a separate indemnity bond. As a seller willing to pay for issue of public notice. Is it proper to sign an indemnity bond with them since the indemnity bond is already included in the sales agreement. Is a police complaint necessary as the original was never received and is not traceable.