I was wondering if there's a definite policy to allow people with two or more reservations with different airlines to have their luggage sent directly to final destination, without having to recollect and check in at intermediate steps; does it depend on previous agreements between companies, on visa/nationality, etc.?
My case is Edmonton -> Montreal (Westjet) and Montreal -> Paris (KLM), with 2:05h layover, ITA nationality, but I guess one would like to know if, at least theoretically, just showing all the tickets at first check in is enough to get luggage tagged and shipped correctly.