Hello Finfin13
Saver Day Passes are valid only in Switzerland. You need tickets from Paris to Basel SBB and from Annemasse to Annecy. Prices are usually cheaper if you change in Strasbourg or Mulhouse and take a regional train from these cities as a direct TGV from Paris to Basel. I suggest to search the best prices on sncf-connect.com. It is too early to buy such tickets for April 2025.
From and to Interlaken, search the timetable on sbb.ch and the best price will be displayed: Supersaver Ticket (valid only in the selected trains) or Saver Day Pass (valid in every train, better if you don’t know when you will arrive in Basel). Please note that the half price will be displayed first, be sure to buy full price tickets, define the name of the passengers without any reduction. Discounted tickets are not exchangeable and not refundable.
Kind Regards
Danhiel