Swapping BA exec club number to Iberia – when?

[Martines1988]

Hi, I’m still not entirely sure around the swapping of the frequent flyer number process.. I have BA bronze but decided to start crediting tier points to Iberia from now onward.

When shall i swap the frequent flyer number? Is it ok to do it after online check-in? or shall i do it before? will I then loose the pre-booked seats? Or once they are pre-booked they stay on? Anyone has experience with it?

I know Royal Air Maroc website works magic for the actual process, just not entirely sure when shall I do it…

Thank you