Originally Posted by
lsquare
What do you mean by DL will protect across separate tickets?
If there are IRROPs that prevent you from "connecting" from one ticket to the other they will generally take care of you as if it had all been booked on a single ticket (it probably requires that the time between flights otherwise met what would have been the Minimum Connection Time, luckily I don't have much experience with needing to lean on this

)
Originally Posted by
lsquare
How would you do this if you depart from YYZ and want to fly to LAX/SFO?
e.g. book the companion ticket DTW-SFO-DTW and sandwich a separate YYZ-DTW-YYZ around it. I think YYZ-DTW is seasonal but you get the idea.