On this page, you can add another Theme Master as a Sub theme. 

How to select one or more Sub Themes

1. In the Theme Master column, mouse-over Actions and select Select Sub Themes....
2. In the Select Sub Themes dialog box, select the required Theme Master, select one or more seasons to be associated with the Theme.
3. To save the details, click on Save.
4. The new theme Master is created and displayed in the Theme Master column. 

NOTE : This will be displayed as Theme Type - [Combined / Simple] on the Theme Masters page.