Form Society without BCC and OC ?

I stay in Maharashtra Pune (PCMC) area , i have purchased flat in 2015 , this is a single building society now its been around year builder has given the provisional possession letter and we all are staying in this building . Now as per RERA possession of this building is in Dec 2022 . Now Builder is saying us since we are staying from almost an year you form a society and start the maintenance . Now we dont have issue with giving maintenance but the problem is since we did not received any Completion Certificate or Occupancy Certificate we dont want to form a society and take responsibility of building . As per RERA the completion date is Dec 2022 so we cannot do anything there . Any suggestions ? Should we form a society or not ? I know legally we cannot form a society without BCC or OC , but builder wants us to do this with mutual understanding . we dont want to take responsibility of forming society because we dont know what might happen in future . This building is 5 floor b