denying of Adoptaion of Son

Dear Sir , Myself Nishikant Brijbihari Rai (34)( Mention in passport , PAN, Degree o BE ,Bank Accounts & all documents.) . My Legal Fathers Name is Brijbihari Rai ( 70 ) & Santi Devi (65) . My Boilogical Fathers Name is Surendra Rai (Died 2008 )& Jaikumari Devi (48). Brijbihari Rai is Elder brother of Surendra Rai & Birendra Rai(63,Handicaaped, still Bachelor ). Brijbihari Rai had one Daughter Jaya Rai Tiwari. Surendra Rai had 5 childrens including me At age of 3 Yrs , Brijbihari Rai ( 70 ) & Santi Devi (65) took me for education & life caretaking including giving their names forever to me. Now there is twist. They denying that I am not the adopted son becuse of no papers and also they are selling my allshares in property ( ancestral which are expected in my favour ). He already selled some part of undivided property in which all are road side. I staying out of this village area and staying in city on rent with my wife. I want to construct a house in village but now no more residencial part of land is remained only balance are farming land.After selling some part he prepared a will & made jaya Rai tiwari as sole nominee as she had made a game plan to put me out of picture from family & property.The money she get after selling proprty , she purchased a plot in her area where she is living with her family. my querries.... 1. Is I am the legal child of brijbihari Rai? If not they who is may Legal father & Mother? 2.Can I challange the will? 3. Before will , Brijbihari Rai selled some valueable part of land including my shares. Now can I challange those partas my shares? 4.can this prorty re-division & sharing can be made ashe also shared my part ? 5. he also made some mistakes while allowting the coners of land in selling documents.Can this points make this agreement void? Thanks for help & support. Nishikant Rai