Here is a link to the rules:
https://www.oneworld.com/documents/1...9-d346ec820edf
In particular, see:
(f) Only one international departure and one international arrival from/to the country of origin permitted
EXCEPTION: Two permitted for origin USA when one arrival-departure is a transfer without stopover.
NOTE - travel between USA and Canada is not counted as international.
8. STOPOVERS
Permitted
NOTE: 1. Minimum 2 stopovers required
2. Maximum two stopovers permitted in the continent of origin of which a maximum of one stopover is permitted in each direction in the country of origin.