[Baron Munchausen]

Yes, only ONE empire at a time can be MEE. Which means that a map dominated by two large empires won't have any MEE triggered. It's too bad but the AI is limited, like I said. If the AI were more complex it could be told to form a 'league of non-aligned worlds' or some such with the smaller empires in any game. If the AI understood 'borders' and 'proximity' it could even form neighbor/regional alliances in preference to others. More features we can only hope for right now.