It would be good to have a facility to select a group that are expected to attend an event and to have a report that analyses how many of the group have registered for the event.
Even better, and perhaps selfishly, member of a group are expected to register for one of several events and reporting is provided for that. As an example, emplyees are required to attend a Health and Safety briefing. The briefing sessions is run on a variety of dates to provide maximum flexibility of choice.
Paul