Is there any body can file the case after registration of site

1) Purchased a site in 24 years back. The layout done by somebody and the Real owner and her only son came registered in our name. Actually the layout was not converted (Revenue Land) which I came know after many years. 2) In 2003-04 I was taken permission from the Grama Panchayath for construction of a house but some unavaoidable circumstance did not do. From the begining till the Selling of property I was paying the Land Tax to the concerned authourity. 3) In 2006 a site one who sold's son filed case of the entire Servey No. We fought case of the schedule property and we won the case in the Hon.Court in the year 2013. We got decree copy and after that we made B-Khata in the Corporation and sold in last April 2016 to the neighbour of the scheduled property. One who purched the site is next number of my site only. 4) Now the daughter the Real owner land had filed case, and made us has 2nd Party. 1st Party is one who bought site from us. 5) Sir, Now I under confusion. Is there is any risk or whether we have fight against him. What do to sir. Can you suggest me. Thanks,