I have found that some groups used solely for organizational purposes are occasionally getting called by users. (In one case intentionally to avoid normal communication channels)
These same groups also lead to questions about membership due to their cryptic naming conventions.

Can we have selectable groups that;
a) will not be announced when a user gives the command "What groups am I in?" (Primarily - Organizational groups that are for permissions... ie Z_Perm_All MD's.)

b) cannot be called - directly. (For Organizational groups that are only used for reports - ie Z_Org_Respritory Therepists)

c) will "capture" users that have belonged to an auto-remove group - ie Charge Nurse groups, so messages can be left to just those nurses that have been in that group for the last XX days.
So, a group called "L&D Charge Nurse Messages" would keep/capture a list of users from the L&D Nurses group that had added themselves to the "L&D Charge nurse" group in the last 45 days. The L&D Nurse Manager could then leave a message for that capture group, thus contacting only those that normally perform charge nurse duties.
I have tried to do this manually... and it doesn't work so well... and every nurse manager "says" that "all" nurses can be the charge nurse... But reality shows that it's only 5-7 out of a group of 50-60.