Limitation of 4 months for registration of conveyance deed is for those cases where full payment is made and possession delivered. 

Ten years to complete construction is another thing.

According to rule 9 of MOF Rule, it ismandatory to take necessary steps to execute the conveyance within a period of four months of registrationof the society

2) builder cannot by agreement insist that he will execute conveyance after period of 10 years 

Complain against builder before consumer forum and seek orders to direct builder to form society of wings constructed by him 

It will be with consent of the members/tenants only

One-Sided Clauses in Builder-Buyer Agreement is Unfair Trade Practice- Supreme Court

In a remarkable judgment, the Supreme Court has recently held that one-sided clauses in the Apartment Buyer’s Agreement constitutes unfair trade practice and such terms cannot bind the flat-purchaser.

Case name: Pioneer Urban Land & Infrastructure Ltd. v. Govindan Raghavan

The present appeal challenged National Consumer Dispute Redressal Commission’s (National Commission) order, whereby the National Commission directed the Appellant builder to refund the stipulated amount deposited by the Respondent homebuyer along with interest towards compensation.

Therefore you can fight out the case on the basis of the above judgment

The owner members of the already constructed and occupying the flats can form a society and issue a letter to the builder to handover the same to society at least to the extent of the completed wings of the complex.

10 years of completion of entire project appears to be contrary to law

the period for conveying cannot be so long

it is literally unconsciencenable

there are umpteen number of judgments in which it is held that once the building is complete, OC is received and possession taken by flat buyers, then builder has to convey the land and building to the society of flat buyers

he cannot just sit over the land in the hope of extracting future FSI and making construction on the land using that FSI

It can be contrary to law because both parties have agreed for the condition of 10 years for conveyance deed.

And builder is not delaying the conveyance deed unilaterally.