Lufthansa Seat Selection

I can't answer about whether you will be allowed into LH's seat purchase section. But I can tell you that over the last several years we have taken 12 legs between Philadelphia and Frankfurt, with connections either after arrival in Frankfurt or prior to FRA on our way home. We never paid for seats, and in every case (i.e all legs) we were able to select decent seating by logging in to LH as soon as check-in opened.
If seat selection is important, I should think you can direct a question to United's Customer Service and ask how you would make the selection you have paid for on the code-share.

Or, have you priced the same flights directly on Lufthansa?

Why not book the flight direct with Lufthansa instead?

I recall that when I had this situation, within the last 2 or 3 years but not more recently, I was able to reserve seats for the United operated legs at the time of booking, but I was unable to book the Lufthansa legs until 23 hours before departure. I was flying in Economy, with the prepaid baggage and seat selection.

Super annoying, but I think I had ensured that my transcontinental flights were United, so it was only my shorter hops within Europe where I had delayed seat selection. And on those flights there were not a lot of pre-booked seats, so at 23 hours I still had a lot of options.

I do recall being able to reserve seats sooner than the stated 23 hours before that leg's departure - it seems like it was 23 hours before the first leg of my flight, as I recall it was a pleasant surprise. But I might be mis-remembering that.

+1 for BooksMusicTravel. It's annoying, but it has worked for me. Sometimes I've had a brief delay (up to 3 days) before the Lufthansa confirmation number was provided to me. I always put both confirmations on my typed itinerary for us to carry, in case I need to know while traveling. I find Lufthansa flights to be more comfortable and better run than comparable United-operated flights.

Using the Lufthansa booking confirmation number on the Lufthansa website, as described above, should work. I have not flown United or Lufthansa, but I have done this on Emirates, Qantas, and Japan Airline flights I booked with our Alaska miles. Alaska gives you the other airline’s booking confirmation number right away.

If that does not work, try the FlyerTalk forum for Lufthansa Airlines; people who frequent frequent FlyerTalk are generally very knowledgeable and helpful.

https://www.flyertalk.com/forum/lufthansa-austrian-swiss-brussels-lot-other-partners-miles-more-495/

I have flights booked through United with Lufthansa code shares for the last outbound / first inbound legs. Also unable to select seats via the web, even using the Lufthansa booking code on the Lufthansa web site. Last year I had the same situation, and was able to select seats by calling their CSR number, but they charged me $60 each way. After I cancelled last year's trip, I got fully refunded for the flights by United (my ORD->MUC flight disappeared) but ended up eating the $120.

This year I'm not playing that game, particularly since I'm only two weeks from departure and still may bag the whole thing.

I just made this same mistake in booking flights through United that are actually Lufthansa's. We're going premium economy because seat selection is key to us. I called Lufthansa and happened to get a great csr. He very efficiently walked through seat selection on all our legs and to my surprise there were still desirable choices left (our flight was three weeks away). He did at first say I would be charged for each leg, but when he finished processing it, the costs did not show up. I then told him I had booked through United and that seemed to explain the $0 charge. Maybe I just got lucky?

Call up Lufthansa and ask for the UA Booking Reference PNR Code. I have booked a mixed airline itinerary before and was able to select seats on the international portion by getting their PNR#. Generally on your E-Ticket it should show you both the UA and LH Booking Reference#s.

Also sometimes partner airlines will not allow you to book seats on airlines booked via Lufthansa or vice versa. Sometimes airlines require you to pay a seat assignment fee and others don't.

United may give you free assignments but then LH may charge you so you would be billed on the LH website. Me personally I don't mind paying for seat assignments to get the ones I want. I find its best to take care of this before you fly. Also seatmaps may only open up 100 days before the flight depending on the airline so you can ask when they will open up to get your fair share of seats.

Good luck and Happy Travels!