I have had several flights within Oz and across the Tasman in the last 12 months with QF all on open tickets as part of a DONE4. I simple rang QF reservations and made the reservation. No need or even any comment about "stickering" the ticket coupon.

I agree that is the way to do it, but my experience with QF in the USA is different. I rang QF, requested the seats, and when I gave them the ticket number, the agent said she could not do that since it was on AA ticket stock. Rather than endure the voice mail on QF to get a 'better' agent, I called AA and was done in about 3 minutes. I really believe that an airline reservation staffs' knowledge on this determines whether it is easier via the RTW desk or individual airlines.

Because the BA "boffins" were trying to waitlist you into a class (D) that doesn't exist on the majority of North American AA segments. As you may have figured out by now, a DONEx can book into "A" class on 2-class North American flights, it's in the OWE rules. And as you probably already no, there is very little "Business Class" within the US, on almost all flights, the front cabin is marketed and sold as "First Class", hence only A inventory, not D. Exceptions are 3-class flights that offer both First and Business (primarily only JFK-LAX/SFO) and flights to Canada/Mexico/Caribbean, where the front cabin is marketed and sold as "Business". Don't ask why.