Passport oopsy

Woops, we hit a snafu in our trip to Spain, before we even left... Somehow, neither my sister, my parents, nor I managed to notice that my sister's passport expired two years ago. DOH! The agent at the check-in counter informed us of this fact. She asked if I would like to travel today as planned and have my sister catch up tomorrow, but sis wasn't too keen on that idea since she'd have to navigate the Amsterdam airport by herself during her connection. Anyway, my mom scheduled a "rush" appointment with the passport office tomorrow morning. If all goes well we will be able to make it to the airport in time to catch our late-afternoon flight; our trip would just be cut short by one day (the gate agent kindly re-booked us on a flight tomorrow free of charge). If there's a delay, however, either I'll have to head off to Spain by myself, or we'll pay a ticket-change penalty to push the departure and return dates back even farther. Egads!