Originally Posted by
FlyinHawaiian
I don't think LH can recognize UA's PNR; there should be a seperate LH PNR which you can get as stated above or calling LH and giving them your flight information. With that information you can go on LH's website and do your seat selection.
Not the PNR - the ticket number. I've had good success with that in the past, specifically on LH.