Since we were talking about getting the messages from the facebook group, for archiving I checked out the developer section on Facebook. I found an API and an online explorer that let my export all the group transcripts.
It looks a bit ugly but we now have a hard copy that I put on dropbox, any images or links to videos will come up and links in the log.
I put it under a folder called 'FaceBook_Chatlogs_Raw_data'. We might need to edit the raw data to make it look pretty for the group blog.