I have an itinerary to Europe with AC on the way out and UA on the way back. On the way out, I’d like to book a flight the same time as the AC one and fly standby the day before because it’s significantly cheaper. The Europe itinerary is booked through LH but because of the UA segments has a UA PNR. Will that cause issues, or is UA only looking at flights on its own metal for overlapping reservations?