What is the complete process for changing surname

After the affidavit did you insert advertisements in an English and Bengali newspaper. If you have advertised you name stands changed.
For the new title Y for your daughter, parents have to declare through affidavit before 1st Class Magistrate. After it is done advertise in the newspapers as above . You can produce the documents before the school authorities who will change the title in school. You have to follow the step at each stage. Change all documents accordingly. For birth certificate you have to give them intimation. The nursing home or hospital where your child was born will have to be intimated in writing will all records.