AA's rate desk in DUB does not have the rules down pack. Only a *few* agents know what they're doing. EMECO had even issued a RTW when the fare was completely wrong and the fare calculation was done by DUB. EMECO just accepts what DUB prices out. When I saw the fare calculation, I emailed EMECO to highlight the fact and they had to queue the PNR off with my notes, and only then was the problem corrected.
I have had a few clients who wanted to reroute after the first segment from CAI. I simply put in the remarks that the client needed to reroute, please reprice from LHR.... DUB will then recalculate and get the PNR ready for reissue. THAT is the correct procedure. However, the agents there tend to leap before reading the itinerary and you'd have to explain everything in clear detail otherwise they think you're starting your journey in LHR! Yes they have returned messages saying that there is one segment too many and I needed to cancel one. Then I had to message them back to say that one segment was on waitlist - hence it shows 21 segments... yes it's like explaining things to a bunch of 5 year olds. Mind you, some 5 year olds know better.
I'm not saying that everyone in DUB is like this.. but it all depends on who you get and how the wording of your request for reissue is taken up. You need to detail everything out to the agent. IF the agent knows what you are talking about, he/she can spell it out to the rate desk and thus get this done properly. The DUB rate desk will usually not take calls from the public. So you'd need to communicate with the AA rep doing the booking for you.
Good luck.