You could quote them their actual wording on ba.com.

They are eligible flights.

Eligible flights

Eligible flights are defined as those flights marketed or operated by British Airways and those flights marketed and operated by Iberia.

• 'Marketed' means the flight will have a BA flight number (in your itinerary or on your ticket).
• 'Operated' means the aircraft that you travel on is a British Airways aircraft (including franchises and BACityflyer).
• 'Marketed and operated by Iberia' means the flight will have an IB flight number and the aircraft you travel on is an Iberia aircraft (including franchises).

Reward bookings and agency or industry discounted bookings are not eligible.

https://www.britishairways.com/trave...s/public/en_gb