I'm trying to book a flight YYZ-EDI and Kayak is showing some reasonable routings via EWR on CO (but all AC flight and codeshare flight numbers). However, if I go to aircanada.com to try and book there, the only flights AC wants to show me are those connecting through LHR, which I want to avoid.

Any way I can tell aircanada.com to sell me the codeshare connections on Continental? I'd rather book directly on AC.com but right not the only option is Orbitz or something.

EDIT: second question... I am currently booked on a BA reward (J) which cost about $600 in fees but can be cancelled with only a $50 penalty. I will likely be short a few Q miles this year for AC Elite. Is it worth it cancelling the British Airways reward ticket and paying an extra $500 for a revenue Y flight instead (CO or AC tickets are around $1000-$1100 right now) for an extra ~7500 qualifying miles?