Add luggage on Iberia flight booked via BA
Just a question regarding adding luggage on an award ticket. I plan to book an Iberia flight using avios, but am not sure on which website is better as I also have to buy extra luggage. Will I be able to manage the booking on IB app/website to buy extra luggage after booking the ticket on BA? Or am I only allowed to purchase luggage on IB app/website when the ticket is issued by IB?
Anyone with similar/recent experience? Thanks in advance.