I'm thinking about flying out of LAX on sunday.. AC's prices are insane, but there is a cheap ticket on AC.com via ORD (on united first leg) on Sunday. I wouldnt want to take that flight since it leaves at 11pm and doesnt get to toronto until 9am the next day. I wanted to do a same day change (50$ at the airport), and take a direct AC flight, can you do that if the first leg is united? My understanding is that the whole ticket would be united's if the first leg was uniteds...