Brother influencing parents to transfer all the property in his name

Dear Sir, After marriage I had seperated from family. My younger brother who is unmarried and staying with parents without getting married. My parents are dilapilated. My father is admitted in hospital due to an old age. My younger brother had taken signature and thumb impression on the blank paper. I am keeping good relations and provising all suppert and love to my parents in their old age. My younger brother is intended to acquire property. Since he is staying with parents he is taking leverage of his conspired demands. His would be wife also supports him in his malignant intensions. Please Help me. My parents seems disempowered going against him. I am not staying with them. I dont want and dont manifest that my younger brother(unmarried) and his would be wife will be succeeded to their illful, ill intended wishes of acquiring property. Please HELP.