To Create a New Sub-group

Click Window menu > Project Manager.
In the Project Manager, under Project list, right-click the project node (at the top of the list), or an existing subset. Click New Sub-Group.
In the Group properties tab, enter the name, file location and the template location of the new sub group.

Note: To remove a subset, first remove or relocate any sheets it contains, then right-click the subset and choose Delete Group.