Hi @chuchu23
Thank you for your request
According to my information, the supersaver ticket can be used, but it’s not possible to make reservations on this train.
For further information, please contact my colleagues from RHB. You will find also all the necessary information here: https://www.rhb.ch/en/service-souvenirs/contact
I already wish you a wonderful travel through our mountains 🙂
Best Regards
NicolasK