Does that mean we have to add this code to the theme?:
/*
Theme Name: X – Child Theme
Theme URI: http://theme.co/x/
Author: Themeco
Author URI: http://theme.co/
Description: Make all of your modifications to X in this child theme.
Version: 1.0.0
Template: x
Please login through FTP and go to wp-content/themes/x-child then check this file style.css and make sure that the file start with the lines mentioned in the previous reply.