Procedure to transfer the ownership of the property to my name

RELIGION-HINDU A vasiyatnama was prepared by my grandfather of the house being resided by families of his three sons. The vasiayatnama is registered. Ground Floor is completely built & is shared by 2 sons. First Floor partially built is resided by 1 son. Vasiyatnama clearly says - that I (grandfather) am the owner of the house till I am alive. After my death my wife (grandmother, passed away) will be the owner of the house. After her death the malikana haq of the house will be of three sons. Now, I am the son of the 1st son of my Grandfather. My father is of 75 years. Q.1) What is the legal procedure of getting a registered will that transfers the malikana haq of house after my father & mother to me? Q.2) As other two sons of my Grandfather have their own family & sons then the will has to be joint OR My father can separately get a will prepared for me for his %age of the share if property is sold OR for the 1st floor of the property that my father is residing??