I booked a multi-carrier itinerary a few weeks ago, and the site was very good at giving me my PNRs for the Brussels, Germanwings, and Lufthansa legs. Brussels was on its own PNR, and the Germanwings and Lufthansa were together on one PNR.

It's a good thing that I copied them down, because the next day, it was showing everything except my UA legs as part of the Lufthansa PNR. Of course, the Lufthansa PNR didn't work on the Brussels site, but the old Brussels PNR that it gave me the night before that I've copied down still works.

The site was ok when I booked the trip though. It handled the multi-carrier, multi-city award booking very well. It kept showing phantom availability on Swiss, so I booked on Lufthansa instead on the return.