https://www.iberia.com/us/our-allian...yers-benefits/

It appears you can get advance seat selection. You probably need to get your Iberia booking number (not the same as your AA booking number), call them and inquire about seating assignments. Pull up a seat map on Aerolopa so you can see what options they <hopefully> give you. Make sure they have your AA account number and Ruby status reflected as well.