So do not sure what you would need to change to stop the British from giving it in the Paris Treaty or eventually being out settled by Americans down the line. But of Brittan did and cooperated it into BNA/Canada , how would that change the developments of the Great Lakes Region? Note, I am assuming that America would still have access to Lake Michigan at the very bottom through OTL Indiana and Illinois territory but that would still put 3/4 of the lake inside British lands and all Superior. Of course Lake Erie and Ontario would likely still be a international boundary.