Should OP start the trip from YTZ (if AC allow) or YXU instead of YYZ? That will put OP at the top of the list.
Or like princess said; connect in YOW;
Although I do not regulary fly LHR/FRA from YOW, I know my research has shown they are easy to, upgrade, and as an SE I would say I get ~30% OP-UP upgrades for flying out of YOW because they do have a tendancy to oversell Y here and J very rarley is full.