Property dispute.

My Grandfather bought a piece of agricultural land in 1983 which had 7 different khasara ( peices of land.1,2,3,4,5,6,7) After purchase he signed an agreement deed with the seller for all 7 khasara. Later when my grandfather wanted to register the land in his name, the seller said that khasara no.7 is on the main road and will eventually go into the national highway, so please do not register this since i will get some compensation.so my grandfather registered 6 khasaras. we have possession of the land till now 2018 may. Eventually the seller died in 1995 and the land went in the national highway in 2013, however half the land of khasara no 7 did not go in the national highway. the sons of the seller received compensation of one half and they then sold of the rest half of the land to another person. Now the other person bought and registered the land in his name in 2014 but he knew the possesion is with us since 1983. He (the person who bought the land in 2014 has filed a plea under section 145 and asked the magistrate to interfear. My question is : 1. what happens in 145? 2. what is the worst case scnerio? 3. what should i do now?