Originally Posted by DanJ

I'm assuming the reasoning for wanting to do this is because the fare from LGA is cheaper than from YUL, right? If so, why bother with the stopovers. Just go to NY when you want to go to London, and catch your flight and go. You could book the stopver on the way home, so you don't have to go back to NY right away, and you still have that leg for future use. Maybe you'll do this again a year down the road, and you'll already have a way to get to New York to start the process again.