Less plot area 920 Sq ft out of 1000 Sq ft on registry paper.

Respected Sir, Here I am submitting my old property matter that one plot of size 20*50=1000 Sq ft which I was purchased by a same owner same plot in between me and my mother. Inside this front 16*20=320 Sq ft was on my name and 20*30 =600 Sq ft of back side was on my mother's name, and from front side 4*20=80 Sq ft was left as entrance internal road for my mother. And by mistake this 80 Sq ft entrance area was remain to take neither on my registy nor on my mother's registry. Later I get purchased my mother's plot in future. After that I want to make paper of all 1000 Sq ft on my name but problem was createddue to 80 sq ft left area. Now I was suggested that make correction deed from the old owner. But he is not ready to come and make correction deed due to long time span passed. Though he is a well educated and a central government service man. Please give me suggestion regarding this matter for he (old owner is not giving me correction deed of remaining plot area) I make lots of request to him but he is threatening what was happened to look carefully at the time of registry? Please any how solve my problem. I am requesting here humbly or give me right JUSTICE.