Hello Leethashea46
Please kindly note, the SBB Community, the platform on which you posted your question, is not run by the SBB customer service; the SBB Community is a customer-to-customer support platform.
If you want to have an official answer from SBB, however, you are welcome to send your query to SBB using this form: https://www.sbb.ch/en/help-and-contact/customer-service/praise-comments/claims-complaints.html
Here is my answer:
I imagine, you are holding a national point-to-point travelcard from Veyrier to Nyon as Nyon does not belong to Unireso. You are therefore welcome to combine your travel card with a ticket from Nyon to Morges, without getting off in Nyon. You simply combine these two tickets, the only restriction, the train has to take a stop in Nyon, and you remain on board, of course.
The ticket combination would not be valid if you would take a non-stop train from Geneva to Morges, which does not exist.
Btw: The SBB Mobile application can only take into account travel cards from regional fare networks and only within the same fare network. As you travelling from one fare network to another, it is unable to calculate the fares.
Kind regards,
Roland