The relevant section of KLM's conditions of carriage (https://www.klm.nl/en/information/le...tions-carriage) mention only an "extension of the ticket validity"; this does not seem to preclude the charging of a change fee and fare difference though. To the best of my knowledge, all this allows is that the return leg can be pushed beyond what would have been the normal theoretical last-possible date on which to schedule the return flight, according to the fare rules. As such, all that KLM appears to guarantee is that the "expiry date" of the ticket will be extended - if the enforced stay was of a duration that the new return date would no longer fall within the validity period of the purchased fare. As such, it appears that the affected passenger will not be told that their ticket is no longer valid; but it doesn't mean that the return can be rescheduled free of any charge.



Hopefully your mother is making a full recovery, which is afterall the most important consideration here. There's never a good time to become sick, but while you are away from home makes it even worse. And, like the other posters above, I sincerely hope the party had taken out adequate travel insurance.