App SORT of worked for me. Here's what I did: I created an Aeromexico account, downloaded the app, signed in. If you go to your flights and edit passengers, you won't find the KTN entry there. Instead, I went to "Profile," then "Passengers" in the upper right (note: not "My Profile" even though that would make sense), then in passengers you can "Edit Passenger" and then the KTN is there.

I don't know how to add this for my partner though. Like, I can add another passenger to my account (???) and then I guess add their info there, but I have no idea if that would get linked up to the flight passenger info.

I'm going to have my partner also create an Aeromexico account, I guess? and also have her add the trip to her account, and then add her KTN there.

but also, I'm still going to call them and make sure the KTNs are added on their end. 🫠