1. This is a common problem which arises if he development plan is not executed keeping all these future problems in mind,
2, In the development agreement it should have been mentioned that after registration of your flats, builder's flat will be registered and you shall register all the flats including builder's share,
3. Similarly the car parking slot also should have been mentioned,
4. However, send the builder a legal notice and insist fot 50% of car parking slit area
5. If he does not comply with, file a specific performance suit againsr him and do not co-operate with him in registering the flats allocated to him unless your claim is fulfilled.