GST on redevelopment of old building

Good Evening,

A old building is under going redevelopment and one builder has been finalized for redevelopment. Builder has given corpus fund to existing members and carpet equivalent to existing area plus additional 20% of carpet area. Following are the queries:

1. Whether GST is payable on Corpus Fund paid to existing members?

2. Whether GST is payable on existing carpet area which will be given free of cost to existing members and if yes, what is rate of GST?

3. Whether GST is payable on additional carpet area given to existing members and if yes, what is rate of GST?

Thank You