Try and see if they can rebook her outbound flights if they change her origin to JFK and her destination to LHR instead of AMS.
Get to JFK by train or bus from Philadelphia to Penn Station and then you can take the frequent LIRR to Jamaica station and then the AirTrain to JFK T8.
Then take Finnair which is comfortable and often not crowded and since it’s a oneworld member there should be no problem for AA to rebook her. Yes it’s a bit out of the way, but HEL is a great airport for transit (no security screening or recheck needed for USA to UK transit) and the non-Schengen Finnair lounge is lovely. If you don’t have status you can probably pay to enter.
Tickets are available now as you can see from Google flights: