Hi SSmith50
A group ticket from Zurich to Luzern is not restricted to a particular train. It is valid in any train on the selected day of travel.
If your flight is delayed, please call 0800 22 00 11 (free number) and we will gladly help you to change your seat reservations. Please note that this Helpline is at your disposal exclusively for questions during the trip.
Wishing you a pleasant journey.
Kind regards
SandraI