My sister filed 498A, 406 and other cases on her husband and in laws after leaving her matrimonial h

My sister filed 498A, 406 and other cases on her husband and in laws after leaving her matrimonial home in Mumbai. She wanted mutual consent divorce from him.She brought her jewelry with her and this made her husband very angry. He got bail in the 498A case and he has decided to take revenge. My sister forgot her cheque book at home with few signed blank cheques which he used to keep with him for paying electricity, telephone and society bills. My sister is staying with us. Now her husband and his friends have filed different cheque bounce cases against my sister & also include us & our parents name.

One case is in Delhi, one in Mumbai and one in Kanpur. He transferred 15 lakhs in my sister's bank account to make FD. The fd is still in her account. He bounced one cheque of 15 lakhs. He may file more cases also. What should we do to save our family from all these false cases? He is very cunning and a lier and he makes false stories. Can we file any case against him to stop him from filing more cases? How to fight all the cases at the same time? He is doing all this to take revenge. Do we need to worry about these false case?