Challenging a will

My mother in law has possessed a house and a land in Guwahati , Assam, about 1 ha of Agril land in different location which was self acuired property of my father in law. She died in the month of Dec 2016 due to cancer which was detected on January 2016. My wife had one elder sister who got married and got divorced . After my mother in law's death my brother in law asked my sister in law to leave their fathers house ( the owner of the house was changed to my brother in law and mother in law's name after father in law's death in 2006) by claiming that mother in law had made 4 wills in the name of brother in law(that means all immovable properties). According to will ,it was made on 24/7/2016 , wills are registered and all properties are in the name of brother in law . Now brother in law filed 4 probate cases in Guwahati. Whether my sister in law and my wife can challenge those will? Now my sister in law is home less and she had nobody to look after. Few points I have noticed in those wills 1. In typed format of the will mother in law's name was not typed correctly so spelling of her name in her signature is different from the name typed in the wills 2. The spelling of the tittle is also wrong 3. The same advocate who was witnessing the will also handling the probate case. So please advice us