My mothers property illegally transferred by my brother

My father owned a house in Patiala his whole life. He moved with me to UK around 20 years ago, leaving only my brother and my brothers wife in Patiala. Since then my brother and his wife have apparently done a fake sale of the house. They have pretended that my father has sold them the house, providing fake signature of my father. My father was not even in India when the fake deal (and fake signatures) happened. We did not know that they did this before now. We have proof (passport) that my father was in UK at the date of signature. However the date of signature is almost 15 years ago, but as mentioned, we did not know of this untill now. Can anything be done to get my fathers house back?