My cousin brother filed a case against my father.

Sir, My name is Vikas Gangwar, my father moved from Ajmer (Native Place) in 1979 to Khetri Nagar for the Job. After that we just went their on vaccation or any ocassion like marriage. My father were 6 siblings (5 Son + 1 sister). Father is the younger one amongs the brother. My grand father equally divided the property among five brothers i.e. 2 rooms each plus the common area. My cousin built their rooms as they required for the business purpose (coaching center) in that property. Before 7 years, my father dug a water tank in the common area for all the family not for single family. Now my cousin have the objection on that water tank and on that they filed a case in civil court on my father that we want to acquire their property forcefully and also threatening them for their new building. They already took as stay on our property that in future we will not make our house on that or make any kind of changes. Kindly suggest that what should we do now, because the case is totally wrong and fraud.