1. You, your mother, your brother and your sister are the legal heirs of your father's share of 50% of the total property,
2. Balance 50% is owned by your mother,
3. Your mother and sister can gift 50% of their shere of your father's share of the property to both the brothers by executing and registering two gift deeds,
4. After this, your mother can execute and register two Gift Deeds transferring 50% of her share of the entire property to each of you two brothers,
5. After this you can file a partition suit to devide and demarcate your 50% share of the entire property.