I may be the lone dissenter here, but I'm trying to figure out what does FB have that competes with a writing forum? Do they have free writing lessons?
I have nothing against FB, but it should not be used as an excuse to pull one away from what is important or of higher priority. There is a reason why FB is dubbed "Social Media." It's a place where one goes to socialize, which is fine. But one could hardly consider it a substitute hang out for those who are interested in improving their writing skills.
Jan, I think you know how much I appreciate the effort and time you put in to make better writers of us all. Perhaps an earlier suggestion to limit the lessons to monthly might be the answer.
I'm not sure how this other suggestion would work, if at all. Perhaps for the new year, you might want to have an open enrollment week ( like other learning institutions) where those who are really committed to "attending" each month would sign up. You might want to include available courses you plan to offer.
This way you would have an idea of interested participants, and those who have signed up might feel more committed to tuning in.
If this sounds too complicated, I'll understand. But it's a thought.
Be encouraged. The results of your effort is like the iceberg. You see only the tip of all you've done to keep many a writer afloat.