currently there is an offer - "Day Pass for 2": https://www.sbb.ch/en/travelcards-and-tickets/tickets-for-switzerland/1-day-travelpass/day-pass-for-...
As one of the condition for this type of ticket is the half fare card. Do I understand correctly, that Swiss Half Fare card (for 1 month and costs 120 CHF) will not work here and I have to have a Half-Fare travelcard (for 1 year and costs 1845 CHF)?
If yes, can I buy in Zürich (Flughafen?), being a German resident?
The confusion is caused by two different answers below via the links