Notification toggle on save and edit

consider (if possible) the send notification toggle still appearing even once the node is saved (and then edited again). An example of where this could be useful is :
Node created and sent out to all group members informing them that "a Group meeting is to take place on Tue 19 Aug" > A group member points out that the date is incorrect as the Tuesday is the 20th. If the toggle is always available then it is simply a matter of ensuring it is ticked > altering the date and then adding at the top of the node "** PLEASE NOTE DATE CHANGE** and saving - then a useful update email is sent.
At /admin/group/content/manage/committee-group_node-article the options could be
NOTIFICATION MODE
* Toggled ON by default
* Toggled OFF by default
If OFF is chosen then it is always available (New or Edit) but OFF. if you are the sort of group that does not use this feature much then you ignore it apart from important updates
If ON is chosen hen it is always available (New or Edit) but ON on New article but once saved existing articles default to OFF. This stops emails being sent out just because you spotted a spelling mistake.