Hello Ghuxumboall51
Yes, you can. You can add further passengers.
If the ticket cost of a half fare Supersaver ticket is higher than CHF 19, the Child Day Pass is the better offer for children.
Just keep in mind the rules for Supersaver tickets: no refund, no exchange.
We do not recommend Supersaver tickets for excursions or when arriving by air. They do not offer any flexibility. More on the use of Supersaver tickets, see:
https://sbb-tickets.cc/en/tickets-offers/tickets/point-to-point-tickets-switzerland/supersaver-tickets.html
Kind regards,
Roland