I see that registration can be completely disabled. I also see that there is a Facebook-connect feature that lets people create new forum accounts using existing Facebook data. Question: how do these two options work together? Let's say I disable registration, but want to give existing users the option to link their Facebook data. Will that work? Can this be done? I don't want people registering new accounts using their Facebook login, but I want existing users to be able to link their Facebook login.