Can I use the transfer ticket from Basel to Zermatt but back from Buchs SG to Basel 10 days later.
Yes, the Swiss Transfer Ticket covers those trips. You can find all ticket details here. Be sure to select "Online Ticket" when asked for delivery options on www.swissrailways.com/ en. That enables you to receive the ticket through e-mail and print it at home.
Thank you Arno