Builder — non cooperation for the forming apartment

Address:

Pune, Maharashtra

Respected,
I have purchased an apartment wherein altogether 7 flats are exist, last 19 years builder doesn't want to form an apartment and on top now he wants to build the another one floor on the existing construction(we don't know the condition of the existing construction structural details etc.).
out of 7 flats , only 5 members are in opinion to form an apartment 2 are out of country and we have all related documentation for only 6 members.
having this brief info. kindly guide us how to proceed further to form the apartment with in this constrain and how to restrict builder from the further construction.

awaiting your response quickly since builder will start the activity by next week.

warm regards
uday