Proper share of ancestral property

This question is regarding my ancestral property. Firstly the property was shared by my father and his brother. Secondly my father has two wives . three daughters from first wife and son from a second wife. how will the court divide among us if we go for a property share appeal? Recently my father (year 2018) after my marriage my father got a document signed at the sub register office from our three sisters and first wife saying he was selling a property. My brother was not present . When i asked how will u sell without his signature he replied it is in name of first wife and he doesnt need to sign. Things are changed after that .... he is totally not taking care of my mom (first wife) not visitng us or did not help when i was carrying my first child... My mom is shifted to the out house. Then thinking of the probabilities i assume it might be a release deed signed without our knowledge (in a hurry/fraud). If this is the case how can we appeal the court to all have equal share in father's as well as ancestral property. Even though if we are betrayed of our share i would like to lock the porperties from beign sold or constructed (something like litigation )