Not sure what you are asking, so this is a "For What It's Worth" answer.
Until you assign a new HC to the exterior light switch, you can not control them independently. Since you have AHP and the CM15A there should be no problem with assigning a new HC, the CM15A will tranceive all 16 HCs. Although you will need an extra RF remote operating on the new HC. BTW Smarthome.com has plug in controllers that have five programable buttons, each button can be programed for different HC-UCs. They are handy when spanning multiple HCs. They are #4071
As far as creating a new module icon for AHP, it will be needed when you can change the exterior light switch to a new HC. Until that time, having a new module icon for the exterior light isn't necessary but does help organize the system.
FWIW