Plot seller not giving plot neither money

My father purchased a plot at a rate of Rs.55/sq.ft in 2002. The plot was of 2000 sq.ft area which makes the cost of the plot to be Rs.1,10,000 at that time. My father paid rs.98000 and didn't pay remaining amount as the seller was not ready to register the plot. The seller were two brothers. They had their problems and they separated. My father did this deal with younger brother who was kicked out of the business by older brother. At the time of registration, He was making us wait just saying that we'll get our plot in a month. Then We got to know that the plot that seller was selling us is not his right to sell. He purchased that plot land from a farmer but he failed to pay the farmer in time due to which farmer filed a case against him.My father was not alone. His friends also purchased plots there and then together they filed a case aginst him. The court then ordered him to pay double the money in 2008 for those who want the money back and plot(when he wins) for those who want their plot. My father waited till now in the hope that seller will give us the plot.  The case between farmer and seller is still ongoing and seller i.e older brother is now saying that he'll return double the money i.e. he'll pay Rs.225000. But in four and five months, he still haven't paid. He just says this week and then fails to pay. Now he says, we can't do him any harm as the signs on agreement is of his brother. Again the agreement is done on 20rs stamp paper on dec 2002. Is this agreement still viable? What can be done? is there a way to get the plot?What action can I take?