False witness

My father's elder brother has filed a falsecase against him in which he is asking for 12 lac Rupees with 24% interest. Around 6 years back he took my dad's signature and thumb impression on a blank paper when my grandfather died. My dad was so heartbroken at that time and he signed the blank paper and gave his thumb impression. Now he has added this false matter on that blank paper.As per the matter he is saying that my father took 12 lac rupees in cash as a loan from him 15 years back. And now he is not returning the amount so that is why he is forced to file a case against my dad to recover 12 lac rupees with 24 % interest fr 15 years and if he is not able to repay the amount then the ownership of our own house shall be passed on to him( this fake point has also been added in the blank paper). Plus there is one of his friend who is acting as a fake witness in the case. As per the written statement of the witness my dad signed and gave his thumb impression in his presence. My dad has never seen this man( witness). Please help.