Property Dispute

Hello, I am a resident of Mumbai living in Prabhadevi, Dadar west. Our building is 30+ years old. Earlier there used to be slums in this place, later a building called Mehra developed the area and gave the people small 25 sqft apartment in the building we are staying now. In 1989 the owner of the building wanted to sell the property and give all the rights of society to the people staying but bcoz of no money to register and buy the rights nobody could buy it and hence Mehra sold it to the person staying in the next building at 5Lac (he does not have any documents for the same) The people staying have their own property documents on their name (aadhar card, ration card, voting ID, electricity bill) We used to give him rent money but after so many years but in 2012 he sent us notice saying that its his property. We hired a lawyer and the case went on for many years. In 2019 the judge dismissed the case as he and his lawyer did not show up for many hearings. His lawyers assistant gave a handwritten application on the day the case was dismissed but the court rejected it as it was not a formal application. Now he has sent us notice again saying the opponents lawyer did not file an application after the dismissal and he wants to reopen it again. I would like to know if there is any chance of the residents winning the case and How?