That's actually a real cool find. I've never heard of that before. How did you stumble up on it?
I don't know the details of how such an organization could come about, but it would require the feeling that the end of the Cold War marked "the end of history," to quote Fukuyama, would need to be more prevalent so all these democracies have a reason to decide to no longer work with dictatorships. So perhaps at the end of the Cold War, have China fall to the democratic forces during the Tienanmen Square protests along with most of the other authoritarian countries like Myanmar and North Korea along with a real thriving democracy to take control of Russia. This will cause a lot of people to agree that liberal democracy has won the struggle for the world and will give reason for countries to establish this Concert of Democracies (gosh, that even sounds awesome saying it).