I booked a trip on AA Main Cabin for my 2 kids under 12 and me. Was a little surprised to see that for the BA codeshare portion, I cannot reserve seats in advance. On the BA website they state: "We'll make sure each child under 12 years sits next to an adult from your booking". That would work well for us three to sit together, given that both kids are under 12. But can I truly rely on this? Or do I need to call BA and pay for an early reservation?

Thanks