The two societies have diffrent nature of building. The builder  will definitely try to get benefit if it is available by combining both the plants in the development authority while developing the other plot and getting it approved in the meantime society has to write to builder to transfer the rights of the society land to society by a conveyance deed so that the ownership of the society should be the resident welfare Association and increased builder wants to club both the properties together the resident welfare Association will have valid. To make objection in calculation of FSI up newly developed plot based on the previous development by including its FSI for the legal action may be initiated if society she is any e development considering the exercise of the existing commercial plot

Before redevelopment of new plot and builder using your building fsi in the new project. You should first apply for conveyance deed whether builder co-operate or not. 

Once procedure is started than it may get complete in next 6 months on very fast track.

So, after that builder won't use your fsi above current fsi passed from municipal corporation.

So kindly check which fsi builder is using in the residential building.

1) issue legal notice to builder to execute conveyance of land on which your building has been constructed in favour of society 

2) builder is required under provisions of Maharashtra ownership of flat act to execute conveyance within period of 4 months of formation of society 

3) he cannot on execution of conveyance use your FSI in new redeveloped property 

1) you can file complaint against builder before consumer forum and seek orders to direct builder to execute conveyance in favour of society 

2) also seek litigation costs from builder 

Issue legal notice to builder to execute conveyance in favour of society 

You will have to apply for deemed conveyance under section 11 of MOFA

Builder cannot use the FSI of your plot 

If you apprehend that he will use the Fsi of your plot then your society will have to file a suit and seek interim relief 

Is society has to take initiative and write to the Builder to enter the conveyance deed in favour of resident welfare Association and they have to built pressure on the Builder to do so normally builders don't do conveyance deed without any pressure violently in fear of losing control over the property

Not conveyance, that only I have said above to apply for conveyance deed procedure.

The builder has no reason to utilize the FSI belonging to your society for the redevelopment of the adjoining buildings. 

It would be illegal and not binding on  your society,  if he does so then file a mandatory injunction suit against him for relief and remedy. 

The builder has to execute the conveyance deed in favor of the society,  you can issue a legal notice to him demanding the same and then drag him to court if he is not complying with the demand made. 

You may discuss with an advocate in the local and proceed as per the advice received in this connection. 

Before that you may talk to the builder about it and exhaust the remedies for an amicable solution. 

NO and on registration of society, automatic conveyance of land in society. No separate CD is require.

For conveyance you need to file deemed conveyance before registrar authority and the developer will complete the formalities for the same. You can apply after 30 days once your society is formed 

This is my response to you:

1. You will have to collectively approach the builder;

2. Pass a resolution in the AGM;

3. If that does not work, then you will have to send a legal notice;

4. Consult a local lawyer, with full facts and take steps.

No he cannot use your FSI in new redevelopment of adjacent property.

Your society should Send legal notice to builder for conveyance deed of your society.