I too have been faced with this issue and told the same thing. One agent suggested I contact AA refunds and ask them to issue a voucher less the change fee since the passengers no longer lived nor would originate in Europe.
Of course getting through to the 817 number is impossible to speak to a person so I sent through a request on the refund website stating exactly what the agent had recommended. Imagine my surprise when I received full refunds to the credit card. All round win for me but I think I was extremely lucky.