...
From the CMS site, open the child course.
Select Tools → Import.
Click the Choose a File to Import button.
Select the .tar.gz file that was previously downloaded.
Click the Replace my course with the selected file button. It may take a minute for the import to complete.
Click the View Updated Outline button.
Restoring key course settings
When a course is imported, all settings from the parent course are imported, such as the Course Display Name. It can be confusing to have two separate courses with the exact same Course Display Name. Therefore, this should be set immediately back to the appropriate course name for the child course.
Select Settings → Advanced Settings.
Registering Students
To register students for the course, use the LMS site.
...