Notification 2.0 API - Send notifications for changes to devices within a group

UC: subscription to the API "managedobjects", context "mo" and a group id as source.
With such a subscription one gets notifications only for property changes to the group itself.

It would also be nice to have the possibility to get notifications for changes to the properties of devices belonging to the group.
Similarly to events and alarms it could for instance take the form of a "...withChildren" api filter.