Is it true that ancestral property once divided becomes self acquired

Sir , My grandfather's property was distributed equally to his 4 sons in 1975 through mutual understanding . Now my father has one son(me) and 4 daughters. My father sold 80 % of his share for marriage of my sisters and now he owns few remaining ancestral property (got through division ) and self acquired property on his name. My father is ALIVE and my sisters have filed a case for share in property . i read on internet that ancestral property once divided becomes self acquired . (CANT FIND WHERE IT IS MENTIONED in Law ) My father is sad for his daughter's behaviour . Kindly suggest