Thanks for writing in!
Because what you are trying to accomplish requires a template customization, we would highly to suggest that you use a child theme. This allows you to make code changes that won’t be overwritten when a Pro theme update is released.
You can find the child theme's functions.php in Appearance > Editor which is only possible if File Editing is allowed. And if not, then you will need to log in to your FTP and browse to
Hope this helps.