My father was born in 1948 and mother in 1952. I have birth certificates for both of them. My father passed away in 1992. In the birth certificate of my father, name is written as "male" only and grandparents' names are written. However, my mother's birth certificate is ok. In the birth certificates of us, we all have some spelling mistakes in father's name and in grandfather's name as well. But my mother's name is correct. For NRC, linkage with mother is enough or will we be required to prove linkage with father too? Is the birth certificate only enough to prove linkage, if not then what other documents will be required?