Originally Posted by
LimeyFlyer
I scanned the responses, but apologies if I missed the plot... same issue for me when I do LH in Europe connecting to UA back to the US... I just take the LH confirm number from the reservsation and then check in on the LH app or website... then generally get printouts at the airport as I'm paranoid about phone failures :-)
you can never check-in with UA if the first flight is not on UA. No exceptions. Once your first flight is in the air you can ... LH can generally check you in all the way via the app or at the airport. Very rare cases in my experience where you have to get your BP in FRA or MUC.