Thoissiewhourr57
Paying a ticket for another person with the HF+ credit is not allowed, the app would throw some error message if trying to do so. And using two different means of payment for the same purchase is also not supported (as with any other online webshop).
Therefore you’d need to buy the tickets with two separate subsequent purchases while selecting the correct passenger and means of payment (= ‘card’ icon left of the big red ‘Buy…’ buttom) BEFORE hitting that ‘Buy…’ button.
So it might be somewhat more convenient to install the SBB Mobile app on her mobile phone as well, using the same login and setting/selecting her passenger details and your credit card on her device.:
Then you would look up a connection and save that journey, the latter would be immediately synced to her device too. After that you would both buy your own ticket for that (saved) journey on your own device with your passenger names and means of payment without having to switch those back and forth. Furthermore, as both tickets will be displayed on both devices, you’d also have a backup in case one of the phones should die in the worst moment (= before a ticket control).