I have a plan for the following trip, is this allowable?

Oct 16 YYZ - YYC
Oct 16 YYC - YYZ - YUL
Oct 18 YUL - YYC
Oct 18 YYC - YYZ

I am only going through YYZ as a connection. The reason for returning to YYC before back to YYZ is just to complete the roundtrip from the Oct 16 trip from YYC - YUL because buying a one way ticket is quite expensive. I am trying to do this itenary because I just need to meet with a client for a couple hours in YYC and then another one in YUL so I don't want to stay in YYC. Is the airline going to bust me for going through/back to YYZ before completing the first roundtrip?

Let me know if this is too confusing, I'll reworded again. Seems like the airline couldn't figure it out when I ask them, they keep telling me it's a circle trip and I can't do it. If I do, I will book this as two seperate ticket, is this a better idea?

Regards,
Empress