Right of illegitimate children on father's ancestral property

Hi Sir, I would like to know the present laws on the rights of illegitimate children on father's ancestral property. If Father had relationship 30-35 years back and a son out of that relation. They never stayed under one roof. It was just walk in walk out relationship. My father had been bed ridden from last 10 years and passed away recently. I had spent huge money on his medical expenses and under heavt debts (most of which are without documents from friends and relatives ). Few days back the son out of my father's relationship came creating mess for share in property. Neither my mother not sisters earlier new about this relationship. Nobody came till my father was bed ridden and I alone looked after all medical expenses.