Hello Michele, I'm researching methods of getting to and from Ireland and considering flying into Shannon and out of Dublin. For the return flight I was confused to see it flies into Dulles and then my next flight would be out of Reagan (DCA). It reads, "Airport change from Dulles to Reagan". I've never run across that before and was curious - is there a shuttle that they (the airlines) arrange or does that mean grab your luggage, grab a cab, and hightail it over to the other airport. Do you have any idea? An email inquiry to the travel site yielded, "Thanks for your inquiry."
Each airline is different and have their own rules. Perhaps a phone call will clarify the matter. Personally, I would not want to make a connection where I have to change airports. It is confusing enough already without having to do that.
Maybe reverse the route and fly into Dublin and out of Shannon to see what happens.