Hi Ian,
In order for you to do the above, you have to use the groups feature. In Method, this is found under Home -> Items -> New Item... -> Group. Once you get to that screen, you can create a Gruop with Items listed in that group. Adding this group will allow you to create groups with sub-items that will populate when you add the group.
Let me know if this is what you are referring too.
Cheers
Denis