How about including a chat room in CB separate from the usual forum? You could also include side rooms within it to enable pairs of users to have a private chat. The only ones I've used are in ICQ and I was thinking of something along those lines.
BUT rather than let it be open to everybody including trolls have users request permission from the Ed to access to it (just a one-off request so that it is available to a user thereafter); that way Ed could have a check to see whether the user is a bona fide contributor to AB before granting access to the feature. Think of it as a bonus for regular site visitors.