Procedure to change the name of mother in passport

I was born on 19.03.1987.i got passport with my mother name as gurmeet kaur in 1998. my mother's original name is gurmeet kaur as per her 10th certificate,ITI certificate.but after her marriage to my father, my grandfather changed her name to manmeet kaur as per ration card of 1994. No other official declaration was made for change of name of my mother.my matric(2003) and birth certificate bears mother name as manmeet kaur. my father got government job in 2001 and he nominated my mother as gurmeet kaur thereafter he died in 2003 and my mother got government job on his behalf in 2004 as name of gurmeet kaur.she is working still now with the name gurmeet kaur now as my passport got expired i applied for correction in my mother name saying that both of my mother name are correct and she is one person having two names.i even got both name changed on my birth certificate from chandigarh administration,as gurmeet alias manmeet kaur.and i wanted my mother name to be manmeet kaur