Please kindly note, on this platform, we are all volunteering travel experts. We have all our jobs and can answer questions here when time permits, mostly in our spare time. Your question is nitty-gritty and cannot be answered by all of us.
So we are grateful if you are patient. If you need an instant reply,what I would understand, please contact the SBB Contact Center which is there for you 24/7: +41 51 225 78 56, from the U.S.: 011 41 51 225 78 56.
That said, see my reply in the discussion we had earlier today:
https://community.sbb.ch/d/37421-shipping-luggage-without-a-point-to-point-ticket/4