Hi,

I have booked a flight from London Heathrow to Guayaquil in Ecuador on a ticket that includes flights operated by both BA and Iberia:

BA458 LHR - MAD
IB6460 MAD - GYE

The booked ticket includes a single piece of hold luggage, but I want to add a second suitcase (and was bought via the Iberia website).

On the Iberia website, it only gives me the option to add extra luggage for the return journey (where both legs are operated by Iberia).
On the BA website, it only gives me the option to reserve seats, not add any luggage.

I have tried to call both Iberia and BA several times. Iberia tell me that I can only buy extra luggage by calling BA, and BA tell me that I must do this via Iberia as I bought the ticket from them.

On my most recent call, where I said that BA tell me to call Iberia and vice versa, I was told that it is only possible to add an extra suitcase at the airport when checking in on the day of the flight.

Is this correct?!
Is there any way to add a suitcase in advance?
How likely is it that BA will tell me that they can't add a suitcase as the second leg is via Iberia when I am at the airport?