confirmation of legal residential status and TDS liability while buying a residential property

I am resident indian buying a residential property at 61 lacs from a seller who declare himself as a NRI and took a 10% Token amount i.e 6 Lacs in his NRO account.
His sale agreement with developer is registered as on 7 Oct 2017 and agrement is silent on his status i.e. R or NRI. He wish to make sale to agreement in September 2018 only to claim Stamp Duty Benefit under Maharashtra Stamp Act , section 25 (5g/a/a). We signed sale to agreement as on12 August 2018 to submit to builder for NOC and Income Tax office to get low or nil TDS certificate under form 13 ( He asked me to sign the last page of application i.e. TCS. But i make him understand that my signature not required). On 13th August 2018 seller called me to inform that his CA is filling his ITR under form 3 and declared his as a RESIDENT INDIAN and he was not aware about this fact. Hence, no need to apply to ITO for TDS certificate. For more comfort seller indemnity himself for any legal or financial repercation and CA Certificate & ITR copy to conform his legal status as a RESIDENT. But, Do not to ready to share his passport copies for last financial year.
I wish to avoid TDS related scrutiny in future from income tax department. Also, Wish to make this AGREEMENT.
Suggest best possible legal solution to get this done.