Brian, I apologize for the delay. I got busy and then when I started to reply, I realized my approach might have been overly complicated for your needs. It was based on a more complicated use case I developed last year for splitting an inventory item into two or more other inventory items.
I didn’t want to lead you down a rabbit hole so I created a little tester app to prove out the functionality. Typing out the instructions will be unwieldily so I can instead just transfer ownership to you so you can look at how I put it together. I would need your AppSheet ID and email to transfer.
The main gist is I scrapped the Swap table. Instead I added a Swap From column to the Data table. It only shows when a Swap is performed. Using a Swap action, the Swap view is automatically populated with the Swap From record and the Building, Cart and Slot fields are automatically initialized based on the Swap From record. There are other ways.
Once the “swapped” record is saved, a Workflow rule is triggered that calls an action (set of actions actually) to clear the fields from the original Data record that was swapped from.
Let me know if you’d like me to transfer the app to you or if you have any other questions.