Editing Group Events
You can edit group events in the future as long as the event is a single group event, or a recurring event with a fixed end date.
To edit a group event, locate the event (in the group calendar or from an individuals calendar) and click on it.
Click on Actions, this will give you the option to edit the event, clone the event or cancel and replan the event. You will also have the option to delete the event if planned for the future.