Maiden name change after acquiring husband's name

Hi All, My wife’s maiden name had FNU in it and to correct it ,she did a name change after adding my name in her Indian Passport. But now we had a baby here and in the birth certificate, the mother’s maiden name is asked for (which contained FNU) and not her present name…which brought us back to where we started
Is there a way that we can get rid of this FNU and change it to correct name on the birth certificate.Any help will be appreciated.