So close you can taste it. Excellent video and excellent app.
You’re first option with the form button is obviously the best, but with the limitation seeing other users passengers.
For your second option, what you could due is create a duplicate sheet of the passenger sheet. That new sheet would be the one you show on the Manifest details page. When you open up the details for that passenger, then you could add a form button that would not show on your original Passengers tab. The only problem is you would have the passenger information in the form, but then you would still need a Choice component to select which Manifest to add the passenger to. It would just be the reverse of the problem you are trying to solve.
I really hope that per user data becomes an option for the Choice component in the near future with further filtering and sorting options later on. I would also like to see the Column Values expanded to show column values from higher up in the hierarchy. That way, if you have lists nested within lists, you could pull values from the first list after you’ve drilled down.
I would prefer option 1, but I will contemplate this for awhile to see if I can think of a better solution.