• Wrong Sale Force Acquisition of land having Sales Deed of 1958 and Mutation on our Grandparents name

We have land purchased in our village by my father grandparents in 1958 in Bihar, Chapra and having sales deed & mutation on his name. We have paid all the mutation / tax fee over the years and have those receipt with us. Recently few goons purchased the same land from the daughter of the lady & aunt who sold us this property after his husband death in 1958. We have filled a case to cancelled the new sales deed and objected the new mutation request based on the case no. filled in Civil court. My father itself is a criminal lawyer and his friend civil lawyer filled a case stating that we have the sales deed since 1958 and mutation since then in govt record without any objection and property is in our possession and at that time daughter doesn't have right as well as her mother was widow since her husband death in 1951. But the key point is that this property was purchased in 1958 sales deed, mutation everything is on our grandparents name. Also before coming to USA my father get a survey done with court appointment commissioner to confirm that land is in our possession with fence and nameplates. We have some police report as well few years back when their was gate theft few years back along with pic.
My father visiting us in USA currently and these goons with local police support broke our names plates on the gate and put some temporarily shaded we heard they got the electricty connection as well. So trying to understand what our options in this case as local police not supporting in absence of my father and not filling FIR which my uncle has given having equal right in the property. 
1. What do you think about our case given the fact we are rightful owner since 1958 sales deed and mutation on our ancestor names? What should we do more to fight the case strongly? 
2. What advantage the other party will get by breaking our nameplates and getting the electric connection in long run when we already have a court commission report showing the land in our possession? 
3. Police not registered any FIR should we ask court to request to file FIR knowing the above fact or keep continuing the fight as civil matter? Can we request court to bring it to original status as before? 
4. Should we continue this as civil case or file a criminal case as well? what's the pros and cons of that.