I cannot have the plugin on all my pages. I run a news site, and I want to use the plugin to talk with only advertisers, not the general readership. Therefore I want to have the plugin on only one of the Joomla articles. There must be a way to do this, no? A search on Google finds that I am not the only one interested in this topic.
It's definitely allowable (by Facebook) to show the Messenger app on only one page. However, JFBConnect was not built with that use case in mind. In general, users of the Messenger feature want it on all pages to connect with their users.
I do see the value in what you're saying, but we don't currently have any way for you to specify specific pages for the Messenger feature to show up on.