I was booking a flight MIA-MAD but went to the seat assignment chart before completing it ansd saw that I was only allowed to make a seat selection on the outgoing leg MIA- MAD (operated by AA). For my return ( an AA flight number that says operated by Iberia), no seat assignment diagram woud come up. I called AA and was told that for AA passengers , Iberia only assigns the seats at the time of the fligh sort of on a standby basis" and you can't select your seat in advance if the booking is an AA reservation. Can anyone give me any insight about this? I did not complete my boolking , but did then try to go on the Iberia website and book it all as an Iberia reservation, but no seat assignment diagram would come up prior to my having to charge my credit card-. I am very uneasy to book on this basis- any guidance?