Ho hum, ya know...if you occupy all of Canada as the USA, then there should be a 'Liberation of Canada' event that pops up at some point. That'll give you Quebec and Canada (combosed of Ontario, and maybe one other region) and you annexing Nova Scotia, New Brunswick, British Columbia, Manitoba, Alberta, etc...
All you have to do is occupy 100% of Ontario and Quebec for, I believe, 1 month...
After that, I just ask UK for white peace and they normally accept.