Circa 2345, the USS Lexington hosted a diplomatic conference with the Antedeans, with Ambassador Curzon Dax representing the Federation. (DS9 - The Brave and the Bold, Book One novella: The Second Artifact) In 2365, the USS Enterprise-D transported two Antedean dignitaries from Antede III to a conference on Pacifica. They were, however, revealed to be assassins that would've blown up the conference by Betazoid Ambassador Lwaxana Troi. (TNG episode: "Manhunt"; Star Trek CCG: Second Edition)