Each pass must have its own Trip. You can't connect two passes to the same Trip. 

If you have both passes on the same phone you must travel together all the time and you must stay together on the train. The experienced travellers recommend that you both have your passes on your own phones. You can create the Trip on one phone and then share the Trip with your fellow traveller just before you start your travel.

To add another pass on the same phone, go to My Pass. There you see the list of passes on your phone, and at the bottom right a + sign to add another one.

Thank you. Yes we are planning to travel together (2 adults and 1kid) in that case do you see any downside of having all passes in on phone. Also we will have only one phone connected to Internet while travelling (and in that phone we are planning to have all pass with one trip) 

Do you see any downside of doing it? Or is it possible that way? 

Thank you for your feedback. 

Thank you. I was looking at the wrong screen. Now I found it.