Hello Powoarrann99
When you purchase tickets, on the screen where the ticket offer is displayed, above the list with the possible tickets, you will find your name and next to it, a pencil icon. Click on it, then choose your name, and tick the box next to Half Fare Card.
To do so for fellow travellers, go to the SBB Mobile app, go to tab ‘Profile’ > ‘Co-passenger’, and modify your personal data there.
Kind regards,
Roland

