Just to add an anecdote for collective wisdom:

I originally planned to fly my LCY to DUB leg but due to an unforeseen work meeting I needed to go back half a day earlier than thought, and was ready to pay for the change fee and any ticket repricing to ZRH.

When I got to the airport, I explained my situation to AA at the airport, at which she point blank said, "why don't you purchase your own ticket from London to Zurich since it'll be cheaper, I'll short check any bags you may have to London, and just skip the last flight to Dublin!"

Not sure this is standard but it appears they are not as strict as I originally thought.