Surname change in cbse 10th marksheet

Sir, when i admitted my sister in the cbse school for 10th then one of my relative written her name as mamta kumawat instead of mamta kumari in the school registration form. her actual name is mamta kumari. and this is proved by her passport, birth certificate, aadhar card etc. all the legal documents are of mamta Kumari. even in the tc of her previous school is also her name is mamta kumari. now when i got her cbse 10th marksheet then i found her name as mamta kumari. after this, i have complained in the school. and the school advised me to go to ajmer cbse board with the documents like her 10th actual marksheet, her her previous school tc give in the new school at the time of admission, and her her registration form of new school. i also have made an affidavit, with the sign of magistrate and i also have given ad. in the times of india for her name change. but when i contact to one of the cbse ajmer officer then he told me that i this is not enough to change the name, where i have to suit a case in the high court. now i want your help, that what to do.