Greeks proper were part of the EU in the Exodus, but you can make them, or a part of them, break off if you desire so. Feel free to look at the independent system "Athena" in the third post's notable independent colonies and see if you want to take that concept and make it more than it is.

We might end up with a sea of minors and middle powers in between a handful of npc's and big ones at this rate XD.