In my experience, agents tend to be very accommodating when an involuntary schedule change occurs. I would scope out the various flight possibilities in advance (as you appear to have done) and call, asking what your options are (mention that you don't want to subject your folks to a five-hour layover if there's any pushback from the agent). I have changed entire reservations, including connection cities, when subjected to such a schedule change. You might be able to change the origination city as well if you ask nicely.