Agriculture Land Patta Passbook Needed How to Get

My aunt is owner of 8 acres agriculture land in Telangana area since 1985 and from 1989 she put 2 persons as a cultivator we dont know what was the agreement between owner and cultivator ... and from 1991 the land became dry since then we doesnt utilise the land now the land is near to city can make plots and constructable, now my question is to our expert lawyers that my aunt wanted to sale the whole land but the cultivator asking 50% share of this land because of he has a possesion of this land of 8 acres since 25 years ... now we have a latest pahani copy of this land showing on my aunty name as pattedar and second name also showing cultivator name as cultivator on pahani ... Now we want to get pattedar passbook and wanted to sale whole land approx 90 lakhs so please help and advise me what is the rights of cultivator ???