I flew Finnair earlier this year on a paid ticket. There was no place to add my middle name on the reservation when it was booked nor was there a place to add my Global Entry number. I called well before check in time and had my KTN added to the reservation. When it came time to check in, I didn't get Precheck. I thought it might have to do with my middle name and called Finnair. Mentioned that my middle name wasn't on the reservation. Somehow they did something to match up the reservation and global entry and I had the precheck symbol on my boarding pass. Not sure if this was related to the middle name issue. I have not had that issue with other foreign carriers.