Just flew on a NH C class codeshare operated by TG in Z. This was a oneway ticket BKK-NRT-YYZ and the only restriction was CAD $15 change/cancel fee.
The NRT-YYZ portion was booked in to D on AC. I'm not really sure about Z on TG but D on AC definitely has a lot higher change/cancel fees but this combination fare seems to have its own special rules.