My brother lives in Canada and in the process of getting residency over there. He has another nationality and not very long ago has acquired B (not sure 1 or 2) visa to the US. He can go back and forth via airports without issues.
I'm a US citizen and we plan to go together to the US by car and I was wondering what he needs to do in order to avoid any issues when coming back to Canada.
As far as I know, he needs to tell Canadian authorities at the border that he's leaving before reaching the US checkpoint, and when going back he needs to tell US authorities the same thing. This is to have his passport stamped on both trips.
Is my knowledge on the matter correct? If not, what should be done to avoid any problems?