I don't know that it is worth trying to plan for the worst-case scenario in too much detail (e.g. using ExpertFlyer) so far out. The likelihood is that you will make your connection; if you don't, as you are all on a single paid ticket, you will likely be rebooked automatically by AC.

If you are really concerned, it may be worth having a list of options (later direct flights YUL-YHZ, or connecting flights via YOW or YYZ) that you could give to an agent on arrival. My experience has been that they have been working on alternatives during the flight and have already rebooked me by the time I arrive.

I recently had an experience trying to find alternatives for my daughter, who was stuck in YYZ during a missed connection, and AC were more efficient in automatically rebooking her than the agent that I was trying to deal with on the phone (on an Elite line); in the end, she texted me to say that AC had emailed her with a new itinerary - long before the call centre agent was able to even look at the flights I was trying to suggest over the phone.