http://www.igniterealtime.org/forum/thread.jspa?threadID=24591

My setup however is a little easier:

• Users of Group E (externals) are NOT shared but simply grouped.
• Users of Group T (Team) are shared to their own members (default) as well as to Group E.
• So Group E (external customers) can see all the available Support TEAM Guys and TEAM mate do see each other (also literally as the sit in the same room!)

• Some of the T boys added E customers to their roster for having some chat. Now things go wrong!
  (BTW When doing so user e of Group E does not get asked for permission! Guess this is because Wildfire is democratic and think it is OK, as the presesence is shown the other was around due to Group T being shared!!!)

The problem: The presence of the E boys is perfectly updated into the WebGui but dont make it to the T desktops. To be more exact it seems that they miss presence CHANGES of the Externals. When new E boys come online the T does not see this. Also E guys leaving stay online in the T roster.
If the supporter T logges out and back in, everything is fine again.
Just for added info: When opening a chat window also the chat window claims away, although the two are chatting like hell. Only file transfer attempts seem to believe in this (wrong) presenence. File transfers dont work with the message "the other is not online!"

------
Gato's notes from the thread:

It works fine only when you make the manual subscription and never restart the server. But if you restart the server (or for some reason the roster or a member of GroupE has to be loaded again) then it is broken. I will try to fix it now.

This one is very tricky and not catchable by the current implementation of the shared group model within wildfire.