Ticketed on AA. We recently had this happen: Booked non-stop BGI-JFK, then that flight was cancelled. AA rebooked us thru SJU, and it threw our segments over the top, but was not an issue, and did not cost us extra segments, or a re-ticketing fee. But once the BGI-JFK route was cancelled, they added a direct BGI-EWR flt, and two of us decided to change to this route. Since it was still considered one segment, there was NO extra seg fee, but we did have to pay re-ticketing for the new airport. Hope this helps!

Robin