My grandson is returning home to Vancouver from Paris via Montreal , all with AC. Does he have to pickup his suitcase in Montreal and go through Customs or can he check in his luggage directly to Vancouver . He is 14years old and I would like to give him the correct information.
Yes he does.
Everyone entering Canada has to clear customs at their first point of entry. In this case it is Montreal.
Your grandson's flight from Montreal to Vancouver will be a domostic one, and there will be no customs facilities at the end of it.
DJClayworth is right but that is only true if you are changing planes. I have personally done this flight before and we were not allowed to disembark in Montreal at all and so we didn't even have a chance to pick up our suitcase but this was a decade ago (Monday, September 7, 2009, AC885, seat 32A). Here's a forum post about this. So: your grandson needs to ask Air Canada in Paris how the connection is going to happen. Or you can let us know the flight number(s) and we can check.