Just so you know you can book BB/AA flights on AA.com, just need to use all carriers option. Really simplifies checking bags too as they can see the rest of the res as some of the agents here can be skeptical at times when your Seaborne and AA reservations are different. Since the agreement has been in place I've cleared all my upgrades out of or into SJU without any effect on the Seaborne segments so I wouldn't worry to much about that. When is your flight? If soon please let us know if Seaborne can issue AA boarding passes yet and vice versa.