Your Question is not clear and in details about the "legal heirs" of your Grand-Father.
If the property of the grand father was his self acquired property then this property shall devolve to all his " legal heir " if he died intestate.
The grandson is not legal heir if his " Father " is alive.
In case father of the grandson died before the death of grand father then grandson being son of the " predeceased son" get the share in the property which his father would have got if alive.
If your father is alive then you dont have any right till you attain Majorityt. After attaining majority you can ask and demand for your right in the property.
Therefore your query is not clear about :
(i) Legal Heirs of your Grand-Father ;
(ii) Your " Father " whether alive;
(iii) Your Age, whether you a Major OR Minor.
So without the about details no body can advise and suggest you rightly as required by you.