Add signups to a Group's 'sub-group'

It seems that the only choice you have for importing your new signups is to which List.

However, our list is organized into Groups. I’d like to import all these new signups via the plugin directly into one of the sub-groups of a group within the list.

Do you know how I can do this?
Thanks!

Oh, and I want to do all this via hidden automation. No ‘click to be added to this group’ sort of deal.

http://ww.wp.xz.cn/extend/plugins/mailchimp-widget/