Property rights of my widow mother

Hi. My grandpa died in March 2019. He had two wives. The first wife committed suicide after giving birth to my father.(we do not have her death certy and suicide wasn't registered as a police case.) His second wife has four daughters and one son. After grandpa' s death my step granny made a property card and mentioned my father as her first child. After 3 months she applied for changes in property card by presenting grand pa' s will. According to will property has been given to the four daughters omitting my father's name.Both entries were made without informing my father. My father died in December 2019. Now according to property card, the home we are living in is actually belong to my four aunts( grandpa's daughters with 2nd wife) Can't we do anything?Does my mother have no right on it?( We do not have marriage certy of mom dad's marriage)Kindly help. We are so worried. Hindu religion