GPA developed property and terrace rights

Hello, We bought a flat in an apartment in Hyderabad. It has two blocks with 70 flats altogether and ample parking, play area and wide terrace. The registration for the flat was done, but we didn't get legal opinion thoroughly due to trust in builder and banks readiness to offer loan. There are two issues observed recently 1. Recently our neighbour pointed out that the total apartment was spread between two survey numbers and half of the land was purchased and rest was acquired through GPA. This was mentioned in the sale deed and registration was completed and loan approved too. However we're concerned that if the person who provided powe of attorney for development decides to revoke their right on property, will we lose our right on the property? 2. As per sale deed, the vendor has the terrace and common areas rights. When we asked during the purchase, he asserted us that he will transfer the rights to society once it is formed. Now, he is trying to stop the apartment society from being registered stating he has terrace and common area rights and would like to exclude them from society rights. What would happen if seller retains the terrace/common area rights and how can we fix this?