Having a bit of trouble attempting to redeem RBC Avion points for an AC flight. It's a multi-city itinerary (just two segments), but the system won't give me the option of booking my return segment on my desired AC flight.

The online booking engine only lists a Westjet option, and i'm guessing it's because my outbound segment is on Aeromexico. The only way I can get AC to appear as the return option is if I select AC on the outbound too.

Has anyone found a way around that? If I phone the RBC agent, would they be able to book this schedule for me (Aeromexico on the outbound and AC for the return)? Thanks