Realize this is an old thread but posting here since my question is connected.

Understand from reading this thread that CX is able to issue onward boarding passes on AC on separate tickets and also check baggage all the way through to final destination in Canada. Any idea if AC is willing to do the same for the reverse leg? Not sure if the 2016 partnership between CX and AC helps.

Itinerary I am thinking of booking is SIN-HKG-YVR on CX and YVR-YYC on AC separate tickets. There is the option of issuing the entire itinerary with CX but I am trying to book premium economy for the CX segments and for some reason tagging on the AC flights from YVR-YYC increases the price substantially and it's much cheaper to book the tickets separately.

My recent experience has been that AC will through-check to a separate ticket on AA flight, so I assume AC will do so for CX, too. I had everything in one PNR though.

Even though CX is able to tag all luggage for you to YYC, you would still need to clear immigration at YVR, then pick up you baggage and then through customs. Then, you would have to drop off your luggage to AC and proceed to the domestic terminal. However, recent changes have made transiting to a domestic flight much easier at YVR, which I think you would be able to benefit especially if you decide to split the booking up.

There is an easily accessible connection desk near carousel 24 and 25, which you can pick up your onward tickets and tag/check your bags again. Also, there are two customs portals you can go through after immigration and baggage claim: 1. Into Vancouver if that is your final destination and 2. Domestic connection to YYC in your case. And by going through the domestic portal, you will be able to clear customs and remain in the restricted area (so no security check required again), check you bags through to YYC and be driven by a shuttle to the domestic side of the airport, which saves a lot of time than walking over.

Hope the above info is clear for you!