In the Liaden universe, has there yet been a connection made between the Trader books (Balance of Trade, Trade Secret) and the main line (Agent of Change, Fledgling, etc.)? I'm thinking it must be through the creation of Bechimo... but I don't recall reading anything directly on point. Have I missed something?
Well, I believe I asked this question just a little too early. The connection is beginning to be made in the newest book 'Trader's Leap', which just came out. The clan that was involved in the Trader books, turns out to have helped colonize a planet with Korval (mainline books), and the planet is the focus of the new book, with both clans coming together in a trading relationship.
Ixin is mentioned in I Dare: "Deliberately, she sought out Korval's known allies and friends: Justus, Guayar, Ixin, Reptor, Mizel"
Mouse and Dragon: "Ixin, allow me to make you known to Aelliana Caylon Clan Mizel, Scholar and Pilot. Scholar Caylon, here is Lus Tin ven'Deelin, who has the honor to be Ixin"
Local Custom: "To make matters even more confusing, it is assumed all persons of melant'i will have a firm grounding in Liaden heraldry, thus opening up vast possibilities for double-entendre and other pleasantries. "A hutch of bunnies," will indicate, en masse, the members of Clan Ixin, whose clan-sign is a stylized rabbit against a rising moon. Korval, whose distinctive Tree-and-Dragon is perhaps the most well-known clan-sign among non-Liadens, is given the dubious distinction of dragonhood and a murmured, "The Dragon has lifted a wing," should be taken as a word to the wise".
a ven'Deelin is quoted in Daughter of Dragons (found in The Tomorrow Log and Dragon Tide).
Korval is mentioned in both Balance of Trade "Korval Herself led the opposition, so the history texts tell us, and at last prevailed" and Trade Secret "On other fronts there was Korval, meddling as always".
Also, the Uncle is mentioned in Balance of Trade.
As for cantra, as it is named after Cantra, the founder of Korval, so I wouldn't consider it mere background content, it's not a dollar or a credit, it's the money minted using Korval's dies.
This shouldn't be taken as an exhaustive list, but yes, the books are clearly related, and not in the sense that Twilight and Anita Blake are set in the United States. The clans at least have a history of interacting, although we don't see it happening on screen so to speak, until Trader's Leap.