I just booked a UA FAT-SFO ticket and a AC SFO-YYZ ticket for my mom (the former was a revenue round-trip nested ticket inside the latter, which is part of a multi-city Aeroplan booking).

What do I need to do to ensure the bag gets checked through? Keep in mind that while I know what words like "interline" mean, my mom does not, and she doesn't like to argue with staff.

I assume that she'll need a copy of the AC ticket (with ticket number) and boarding pass at check-in at FAT? Should she just present that, and say "Please check this bag all the way through to Toronto."?

This is the one part of her trip I'm somewhat worried about, so I need to make sure I have a set of very simple instructions for her.