Originally Posted by
Synthesis
So for:
Brussels > Toronto (via Montreal)
Toronto > Vancouver
Vancouver > Chicago
Chicago > Brussels
Book via United? via AC? Or Brussels Airlines?

or doesn't matter
Doesn't really matter as far as getting your miles credited to MP if it is put in the booking. However once you get status with MP then you will need to ask someone more knowledgeable about the program than me in regard to what way is the best for getting upgraded.