legal heir died

If it is your father's self aquired property, no need to take signatures of your Grand Mother's legal heirs.

Thanks for your response sir.  My father was a business man, I am unable to find his incometax details so I am wondering how to prove that this his self acquired property. Request you to let me know if there is anyother way to prove it.  Or if ther is anyother option to avoid getting the signatures of my Grandmother's legal heirs.

If you can go Incomw tax you can details or your father's property registration documents you can know.

agree.

This statement

The following three persons were mentioned as the legal heirs in the my father's legal heir certificate

is fallacious. There is no such certificate. Succession certificate mentions all the legal heirs. How was 'legal heir certificate' as you mention obtained? Who obtained it? The court has to be satisfied with details of all the legal heirs before granting it. 

Please clarify. The information is too sketchy and incomplete.

 after your father's death and before your grand mother's death, the time  - your grand mother is the 1/3 sharer of the property.

Hence her legal heirs have interest on her death.

you need to get consent of your uncle and aunt too

What do you mean by " In my father's legal heir certificate"? What is this piece of paper? Is it a duly executed Will? Who obtained it and who granted it?

wwhether Your quarry seems incomplete. Wether the alleged legal heirship certificate was duly excuted in the revenue record? if yes then no way  and after death of your grand ma all her legal heirs have become now owners in 1/3 share left by her and now they have also say in the house being co-sharers and now you will have to negotiate with them.