How do I claim ownership with adverse possession?

My father bought a land of 13 marlas in 1993 and construct a house in 1994. The seller execute sale agreement in the name of Pritam Singh ( my nana ji). After that my father due to lack of awareness didn't executed registered sale deed. In 2012, we decided to sold our land but due to some reasons not sold. In 2012, the real owner executed power of attorney in the name of Pritam Singh ( my nana ji). At present, both died. But the land is not registered on our name. Recently I talk with patwari he said there is only 20 marla of land on the name of manjeet singh ( real owner) as per jamabandi. The son of manjeet singh lived in our neighborhood having 20 marla of land. So, my question is that if there is extra share of Manjeet Singh other than there residential land there we can transfer extra share. But unfortunately there is only 20 marlas.Should I approach court for title decree?