NET MS Project TaskGroups

I currently have the following code:

        GlobalVariables.mppapp.ActiveProject.TaskGroups("Category").Delete()
        GlobalVariables.mppapp.ActiveProject.TaskGroups.Add("Category", "Category")
        GlobalVariables.mppapp.GroupApply("Category")

This works fine, but I need to add multiple groups so that when I apply it there are groups below each group.  How do I add multiple groups?

Any thoughts?