The available material does not establish whether the selling carrier's or the operating carrier's fare rules govern a change on a codeshare. It therefore cannot support a universal answer that either carrier always controls; the specific booking must be checked.
What the guidance establishes
The cited guidance says fare rules are based on the departure and arrival country. It also says that changing an existing booking, including a change of fare type, can bring new Fare Rules and fees.
Neither statement identifies which carrier's rules apply to a codeshare change or explains how the country-based rules interact with the selling and operating carriers.
How to check the booking
A reader should:
- Check the exact fare type and route, including the departure and arrival countries.
- Identify the carrier involved in selling the itinerary and the carrier involved in operating the segment.
- Before changing the booking, ask the relevant carrier to confirm which carrier's fare rules would apply and whether new Fare Rules or fees may apply.
That confirmation is important because the cited guidance says a change can bring new Fare Rules and fees, but it does not identify which carrier's rules would be used.
What still needs confirmation
The available material does not provide a universal hierarchy between the selling and operating carriers, a codeshare-specific fee, deadline, or change outcome. Those details remain unconfirmed and must be checked for the exact booking and fare before a change is made.