wignu Honestly not too sure on what you are driving at with your last paragraph.
Let's say you have a tag "priority" and you configure that one to allow create and view by members. You allow private discussions in that tag. Within the admin area you can specify that specific user groups and users are assigned to each new discussion in this tag, this in addition to the using starting the discussion.
As a result each new discussion in that tag will be private by default and visible only to a specific preconfigured group of users.
Visually the users will be immediately added when the tag is selected and the recipients selector will be disabled.
Hope that makes more sense ?
wignu am I right in thinking that if you did have an option of separating it out it will create another set of programming problems??
Separating it out is not an issue. The effects that private discussions disappearing from the index without proper visual indicators is though. If you're able to brainstorm a bit in an issue on the GitHub repository, then I'd be more than willing to consider an implementation.