Hello. We already purchased our train tickets on SBB.ch (Luzern to Baveno Italy). We would like to reserve seats. Is it possible to reserve seats after you already have tickets? I tried Trentalia - it says this is not allowed.
I am following these instructions
Go to SBB.ch
Select the desired route, time, and travel date
Click on Tickets from CHF xx. xx
Click on the pencil symbol to add additional passengers
Scroll down and select Seat reservation only
Choose the desired compartment
Click on the Seat reservation button
Click on Accept and complete the purchase
But I do not see a place to “Select Seat reservation only”
all I see is "Seat Reservation. None. CHF 0.00
Does this mean it is not possible to reserve seats?
The trains are IR, IC, S, Reg)
Thank you