How will property be divided among heirs and reclaim land rights?

My father married my mother, who passed away one year after my birth. He subsequently remarried and has four children (three daughters and one son) from that marriage. My father owns 50 acres of property. How will this property be divided among us, and what share will I receive? Additionally, I own 40 acres of land inherited from my maternal grandfather. My father's brother took 20 acres of that land as a gift deed when he and my father partitioned their properties 30 years ago. Can I reclaim that 20 acres, considering my father and his brother had no right to it? Lastly, can my father's second wife's children claim a share in my father's property? Please provide legal advice on these matters.