I recently booked a trip for my family to go to Europe. We have 3 flights each way, including flights on Alaska Air, American, and British Airways.

The flights were all booked on AlaskaAir.com using points.

We were able to choose our seats for the Alaska legs of our trip, but not the American or BA flights. Is it possible to do this?

It's not uber important that I choose my flights, but there are 5 of us (including kids) and we want to be seated together. Location of seats on the plane is not as important to us, just want to be together.

Does anyone know how I go about picking my seats on BA or American flights already booked on Alaska points?