I also booked the second round on X.de. Flying on NH and DL on NH ticket stock. I checked after reading your post and all my flights are the same.
I would prefer to fly NH on the transpacific leg but haven't been able to achieve that, despite a 15 minute schedule change on the last leg. Any suggestions on doing this prior to leaving would be welcome.
(ps: thank you for the responses re: hidden city concerns)