1. If your father is one of the shareholders of the property then the sellers are required to take your father's signature in the ale deed or should take POA from your father, 2. In the said sale deed or POA payment of his share should have been mentioned, 3. How and in what capacity your father's elder brother has collected the share of your father? 4. If he was authorised to collect money for your father and now refusing to pay him, lodge a police complaint against the said person, 5. Your father can file a Recovery Suit against his elder brother claimh his share with damage and interest on it.