Regarding capital gains

Example: Mr X Purchased the property in the year 1992 and gifted to his sister's through the "WILL" in the year 1997. After that they have entered into the developement agreement with the builder in the year 2012. After the smooth flow of work person Y came and started quarrel saying that some part of the land belongs to him. After enquiry the owners have came to know that it some part belongs to him. To resolve this issue the owners have paid a sum to him and purchased the land. Date of Purchase say 25.07.2013. And they have started selling the flats the 1st flat sold on 06.11.2013. Date of Agreement with the builder is say 07.07.2012. Now the Question is: Can i take the benefit of indexed cost of Aquisition for the flat sale on 06.11.2013 which they have incurred for purchase additional land on 25.07.2013. While calculating the capital gain it will result in Long term Capital Gain without that additional land aquisition. Difference between additional land taken and sale of 1st flat is less than 3 years resulting in short term gain.