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You might look at
fbcomment module. It was written to allow per article customization of the open graph presentation to facebook. Maybe it can be useful, or give you some ideas.
I will mention, that facebook changes the rules on a regular basis, causing what worked yesterday to not work today
In the fbcomment open graph editor, there is a button to check on what facebook actually sees, and what it thinks should be fixed. Every so often the module needs some tweaks to keep up with the changes. I've been busy with other things lately, so if anyone wants to give it some love, please do!