Thanks @RolandP for your answer.
In this case, and just to settle the issue, I understand that the only solution is to buy the regular tickets and that’s it, right?
Please note that my companion and I will move around the country with my relative by car except one day, we will have to go by train from Lausanne to Zurich to spend the day and return so buying any of the cards or offers do not fit our case since we only need to take a train there and back. Nothing else.
I had thought that maybe my relative, as a resident or possible holder of one of these cards could buy tickets for us with some kind of discount or that there could be some other solution.
Either way I thank you for your reply.