Dur to surname difference there is problem in claim as legal heir

My surname is different than my father's surname. It is changed by my father during admission in school starting (Since nursery entry). Now i have School LC with changed surname, in Pan card and passport also changed surname. Now as i have these two strong government documents with father's name with different surname. Now the situation is during claiming as legal heir in agricultural land after death of my father(With due pedhinamu, affidavit, death certificate) they are entering my name under legal heir with father's surname only. They are telling as a legal heir surname should not be differ. In VF6 form in e-dhara (https://anyror.gujarat.gov.in) Dy. Mamlatdar is changing under VARSAI HEAD as :-My name ,father's name and father's surname instead of my surname. As with my father's surname i have no any single document and they are generating the same with wrong entry and telling u should not have different surname as legal heir. They are advising for gazette notification for change of surname. Now i had never been identified by my father's surname in any document then how gazette notification can be produced? i have all the documents with single surname & father surname as different. I have pan card, passport which is self explanatory for relationship of me and father with different surname. Can anyone guide in this matter. Kaushik-Gujarat.