About dishonouring a son (50 yrs) from ancestral property

My father is a government employee. he left his house for job 25 yrs ago with his wife and there was family dispute also due to which my father and mother were not allowed to visit there native village through out their life. my father has 2 siblings one elder brother and one younger sister.my father was given very less share in agricultural land that too only for cultivation. now after 25 yrs he demand his share in property but my grandfather refuses to give him his share. elder brother of my father influence my grandfather to say no. my father was not given even any share in any other immovable or movable property possessed by my grandfather at the time when he left his house for job. he was not even given any single penny to settle down in city. now when my father demanded his share in ancestral property his elder brother scolded him and told him that he will not get any share and he will be soon dishonoured my his father. my question is whether my father can be declared dishonoured from ancestral property by my grandfather..????