Land dispute claim

My father and his two brothers had 9.75 decimal land in my village out of which two brothers sold their equal share of 6.5 decimal to our neighbor according to a sell deed dated1980 shown by them which we are not having and we are left with 3.25 decimal+(3ft vacant land in front of the plot to walkthrough which is not being claimed by any one) now what happen they are claiming .5 decimal from our 3.25 decimal to walk as their plot is behind our plot and also have govt. provided road to walk but they are claiming to take the .5 decimal and 3 ft. in front of our plot which we are objecting not to give as the .5 is coming inside our 3.25 decimal and 3 ft. plot is in front of our 3.25 which is being used by us since 1980 and no one claims to be anyone’s and neighbor is claiming that he ll use it as a common walking land but due to this dispute our relation Detroit with them and we don’t want them to come this side rather they use the govt. road provided to them. Neigbour is threatening us to file a case against us due to that sale deed don’t know how to proceed