Buying ancestral property...

Iam willing to buy a LAYOUT PLOT (Part of ancestral property, got 24 yrs back through a PARTITION DEED) from the seller. On asking about the REQUIRED SIGNATURES ON THE SALE DEED at the time of Registration, He told me that he will only PUT SIGNATURE on the sale deed, he is not willing to bring his family members(Spouse, Single major Daughter) to Sub-Reg.Office & he is ready to provide NOC from them. My Queries in this regard: 1) As it is ancestral property... Is it mandatory to get all their SIGNATURES(As vendor & witnesses) on SALE DEED ? 2) NOC from his family members(Spouse, Single major Daughter) -- Is it acceptable as per Law ? or any other Solution available ? --Kindly guide me !!