So is it possible to add KTN prior to check-in? I only see the possibility of adding passport info like Danemark is showing. With LH last year the dimwit at check-in mixed up the KTN with my son's (who does not need it for security) so I was rejected and had to go back twice. (I found out that it takes time for the system to update; there was no queue at security so got back too quickly.)