Allow user id and user/group right in collaborativ mode to enable specific bahaviour
If you build a project from this structure, you can need to protect some data from public view.
If you want something from collaborativ user, you need to detect this and make a feedback (ex : to know where users have add ideas, where is the mouse cursor, which nodes have been expand/collapse (or another action), etc.).
I don't know if scripting could be used (or if develop each time something would be best).