Father’s will and inheritance

Hello sir/ madam My father married my mother and had 2 children (myself and a younger brother). My mother passed away and my father remarried and he has a son from that marriage. Two years ago my father made a will on his ancestral property (which was from my grandfather) dividing the property among myself, my brother and my step brother. Now my father passed away. Currently we came to know that he had an illegitimate daughter before (who would be the eldest of all the children).Even before his demise, the illegitimate daughter ( whose mother is from scheduled caste in Kerala) of my father has reached the court to claim the property. Please can you advise on what will be consequence of the will made by my father. Will the property be divided among the people mentioned in the will or the will by my father be ignored according to the law and given to all the children, current widow of my father and the illegitimate child’s mother? Your advice would be of much help moving forward. Many thanks !