A real thorny issue for the ticketing gurus as it pertains to the new BA avios earning scheme.

It has been stated here that date changes ONLY result in a revalidation of the ticket. A new ticket is not issued. So, what happens when I change the date of a flight after 18-Oct-2023. Will BA see this as a reissue and therefore use revenue for my 3 AA segments or will it be distance based? I'm mainly worried about my DFW-LHR AA flight as it would go from 14K avios to maybe 5K avios. My ticket was issued by AA in July, ex-TYO.

Any insight is greatly appreciated.