can ancestral property sold without the concent of legal hei

hello sir good evening My great grandfather got two marriages (when first wife die he got anather marriage) both are blessed with a one son. first wife son (mygrand father and grand mother) passed after when my father(born)in 1920- 25. my father was suffering from ill health (fits) so he was not exercise his rights and he died in 1960 after i was born.so the total property enjoied by second wife and his son. in 1941 second wife son sold 3/4 acer. and his wife(not a legal hair) 1/2 acer (when my father is alive)without the concent my father. now layers say itwas bears limitation period not possible to recovery becouse the buyer is enjoyed a long possession. but in 1941 second son wife has no right to sell this property without signature of his husbend and my father. sir please give me solution to my problem thanking you sir