Here you are modeling your users. Each context has a conference manager. Some are automatically set up like chat role describes participant s responsibility and authority, socially. Another interpretation is that role restricts access rights. So if you want to assume a role, your access control will limit your authority.
Most groups use video for presence detection.
JCS is more a toolkit than a finished and tailored collaboration software. Esp tailored clients. Mirror how you are doing business. Going back and forth between flat and hierarchical. Context Directory contains contexts.