My wife and daughter will be arriving by air in Rome on April 17th. From the airport they will use the Leonardo Express to get to Rome Termini where they will catch a train to Naples and then on to Sorrento. Since they are flying and scheduled to arrive in Rome at 12:30 that day and then to allow time for customs, train to Termini etc... I'm uncertain about buying a ticket/reservation prior to departure since I don't really know which train they would catch. Schedules appear to run about every 30 minutes. So real question here is do I need to have a reservation (and what hassles to change it if flight is late or whatever) or can they expect to make a reservation using the machines at the station and get a ticket when they arrive without problems?
TIA
Ron