I have booked TUS/SLC/LAX/SYD in late January. Since SLC is in the snow belt I am wondering what I do if, when I check in at TUS, flights are all delayed because of snow in SLC. This is DL's only route from TUS to LAX unless you want to fly to Atlanta the night before. The ticket was upgraded from M with mileage and is booked in Z class from LAX to SYD. I would rather fly to LAX the day before to make sure that I do not miss the SYD flight but DL says there are no changes allowed with my ticket. I have a two hour connection in LAX. Just wonder if there are any other last minute possibilities if SLC is snowed in. If I pay for a non-stop UA flight TUS-LAX will the remainder of my ticket be valid from LAX to SYD?