Adoption dispute with mother

Hello Sir, I was adopted by my father's elder brother (my dadaji) and his wife (maa). I called them dadaji and maa respectively. My adoption was done orally, there is no formal legal documentation done by anyone. My education and brought up happened with them. I got job in year 2006 after that I am staying away from my hometown. My marriage in year dec-2009 also done by dadaji only. I used to send them some money every month for house expense. Dadaji had 17 acre of farm land in his name, which is not ancestral property. He got this by donation of his uncle. We used to stay together my parents dadaji maa and my younger brother till dadaji was alive. My dadaji died on Dec-2012, and my maa started staying with my cousin. After my dadaji's death his property came into maa's name, that time she told me she will give half of the property to me. and sold half of the property which is her full share. Now she is denying to give rest half of the property to me. She does not stay with me as I live in other city for work. I have only my marriage card where dadaji and maa 's name has appeared as my parents. Is there any way I can get my name in the property? how can I get my share in the property. thanks.