Partition of lease hold built structure

Dear Expert Contributors,

My grandfather had acquired a Leasehold land in the late 50’ s or early 60’s

Soon after his death, my father and his 2 sisters arrived at a family settlement in line with the wishes of my grandfather and accordingly their names were substituted as co-lessee/s in the records of L&DO and Mutation carried out with MCD

As part of the understanding, my father got 2 floors (1^st and 2nd) and his 2 sisters shared the ground floor equally.

While the property remains to be leasehold till date, in the year 2006, my father’s 2 sisters sold their share to party X by executing a registered agreement to sale along with registered GPA.

 My questions are as follows:

Is the Sale made by a co-lessee of a lease hold property, by executing a registered GPA and Agreement to sale (GPA/SA executed in 2006), legal in view of the recent Supreme court Judgement ?

Is the party X (purchaser), the new owner with all rights and titles?

Is the GPA/SA sufficient for mutation of property with MCD and also for substitution of name with L&DO in favour of party X?

 Can party X ,  seek partition of the property as undivided equal share?

 Who is entitled to the development of the floor above 2^nd?

regards