I must be missing something simple.  How can I create a data view that picks up everyone in all the subgroups of a Top-Level Group? 

E.g. I want a list of everyone who attends ANY of the small groups in Section A.

I would have thought that a data view that applies to Person, Filter Type 'In Group', and Group name 'Section A' would pick up everyone in all the the subgroups under Section A, but this doesn't work.  (I also expected to see the Members of 'Section A' to be the members of all of the sub-groups that make up Section A - but this doesn't happen?)

I know I can build up a data view by selecting each individual sub group by adding a new filter line and selecting the specific sub groups, but I would like to be able to select at the Top-Level Group.  What have I missed?