What can I do if someone else has fraudulently registered their ownership on land records?

One forged document has been submitted by my related to district civil court. As per the preliminary information the forged documents are an agreement later where my mother forge sign is available on the revenue tickets pasted in A4 size paper with three witnesses. Agreement later has been prepared on blank A4 size paper " In the agreement letter it is mentioned - my mother has taken 3.5 lakh from the relative for treatment of my father (to paid to medical Centre during father's cancer surgery) with commitment the land will be registered to his name. This is 100% false / feck document, my mother had never discussed and never signed like the document. all three witnesses are also forged, they are his friend. In 2019 March when my father was suffering from cancer at that time i paid from my account to medical Centre for surgery and other treatment. its proof available with me. Sign of matching with my mother sign. so, we are in trouble.