KL803

I just want to share my experience in LHR: My itinerary was ZRH-LHR-ICN-MNL with first leg on LX but all one booking through KE. I was able to check-in at ZRH and get all boarding passes until my final destination, bag was checked through as well. Following a gut feeling when flying a mixed airline/alliance itinerary, I visited the transfer desk at LHR T4. The friendly lady there issued me new boarding passes and scanned my luggage receipt. Out of curiosity I asked, if it would've been OK to show up at the gate with my boarding passes printed by LX. The answer was no, and truly, at the gate there were several calls that boarding was only possible with a boarding pass issued by KE.
So if anyone else is in this situation (mixed airline/alliance itinerary), make sure that you have a KE boarding pass. Get it from a transfer desk or latest possibility at the gate before boarding starts.

miamiflyer8

Fairly common practice. I’ve had this happen on AA, AY, IB, BA, UA, SK. If bp is printed on the respective card stock it’s easier for the gate agent to see that your doc check was done.

mikesaidyes

It's been this way for years and at the gate they always make an announcement. For instance, ATL-ICN tons of domestic Delta connections to ICN and they announce to come up and trade your Delta boarding pass for a Korean Air issued one.