Validity of legal heir certificate issued by the mandal revenue officer.?

My father ped away all of a sudden leaving behind my mother, two married sisters and me(only son).All our property is earned by my father.Part of it has been registered in my sisters names.The rest of the property has been registered individually in my father's,mother's and my name.His intention was that after my father,i should be the sole heir to his share.Knowing his intentions, my sisters and my mother have given their written consent to the local MRO(mandal revenue officer) for my being the legal heir to my father's share.The MRO has issued a LEGAL HEIR CERTIFICATE in my name, for my father's share.How far is this CERTIFICATE valid ???