I had the pleasure to fly with D-AQUI in may, my missus showed up with two tickets for a roundflight over Munich

So did I; two days later… 😉

… although managed within the Lufthansa ticketing system.

Not quite; you buy tickets from the Lufthansa-Berlin Stiftung, but it flies under a Lufthansa flight number with a “J” for Junkers added to it. And you can’t claim any Lufthansa bonus miles… 🙁

… but always a Ju 52/3m with the three engines…

… whereby it’s worthwile to note that it has P&W R-1340 engines, as well as three-bladed propellers and ugly exhaust mufflers (the latter two features to avoid too many noise complaints…). We get to see the Swiss Ju 52’s (with BMW engines) in Munich quite often, and they do sound a bit different