We have a large area in our hospital we call The Treatment Mall, comprised of several rooms, courtyard, and gym. It would be useful if any staff attached to APs in that area (for more than 5 minutes let's say) could be added to a Treatment Mall group.  I could then Call or Broadcast to that group with special messages intended for staff who are in that area.    When staff are no longer connected to those APs, they would be removed from that Group.