Property Land Dispute Issue between neighbour

Hi All, My grandfather purchased a plot during 1945 of plot size 40 x 50. He constructed a home for an area of 33 ½ x 50 and left vacant land for plantation. The neighbor who purchased the vacant site after 4 years near to our site constructed the home in his full site and there is no space for him to walk, so he requested to my grandfather for a space for walking, were we had our garden. My grandfather also accepted for walking but not sold to him. After 7 years the neighbor started fighting with my grandfather that the vacant land let for walking belongs to him. After a big quarrel they made a separate agreement that the total site (combined both property of my grandfather and neighbor) can be separated equally i.e 33 ½ instead of 40 feet against my purchase agreement made in 1945 in village panchayat. But no were mentioned that my grandfather has sold our property of 6 ½ x 50 piece land to the neighbor. When I take and see the EC for my parent document for 50 years from 1945, there is no EC against my parent document. Whether I can file the case against them to get my vacant site back ( still now the vacant land is empty and nothing constructed on it.) All, please help in this matter.