I've got 2 credits left on my SouthWestern Sun Pass. Due to AC recently dropping flights between YEG and LAS, it's making getting back from LAS in June very difficult for me. Both options are connecting flights that require an overnight in either YYC or YVR. Now I can get a flight from LAX-YVR-YEG (1 flight pass credit) in the mid-afternoon, but it requires buying another ticket to get from LAS-LAX. Is there a way to combine this separate ticket with the flight pass?

I'm planning to book a *A airline but I don't want to be left holding the bag should that flight get delayed and result in me missing my LAX-YVR flight. If it's not combined, I'd assume that AC has no responsibility to find me another flight since they are not ticketed together. Anyone have experience with something like this? Am I SOL? Thanks in advance!