Originally Posted by WesternCDN

I'm not sure that 5T's system interacts that closely with AC's anyway. I flew YFB-YOW-YYJ on a 5T and WS combined fare and they couldn't issue my WS boarding pass when I checked in. The bag got tagged all the way through but I had to go to the counter in YOW for the boarding pass.

You could also try calling their local numbers (not the 1-800 call centre), though unsure if they ever answer the phone at the airport.. 867-979-8339 or 867-979-8336.