Iberia use Amadeus as a booking back bone, but they have their own operational reservation system known as Resiber and a different GDS to Altéa, namely A-ICE. So what you may be seeing is Amadeus' view of Iberia, but not Iberia's view of Iberia. So you best call up Iberia to see whether they can help, but it wouldn't surprise me if you have to just do it all at airport check-in. IAG has collected a vast number of systems, no two airlines use the same system, though Level is fairly close to Iberia. Even Iberia Express has a different system to Iberia.