girl's father

Girl's father not happy with the boy

Q: One of my distant relatives, we both like each other and want marry. My parents are ready for the relation, however the girls father is not ready to make this relation with us. The girl and I want to marry.

1. Is it right if we do nikaah with shari witnesses without her parent's permission (she is underage according to India's rule i.e. girl is 18 or above years old.)

2. Can we do nikaah and live separate from each other until she turns 18 years?

3. Once she is 18 years of age, can we marry through court registrar?