Let me know if this diagram sums up your problem correctly.
“Add Row” as a separate action does not allow you to utilize “this item” in the same way a form does. When you use a native form to write to a new table, show details > this item would do the trick.
To do what you want here, you would have to:
- Write the newly added row’s ID somewhere in the Structure Details table.
- Use a relation to relate that ID to the Service Tickets table.
- Show details screen > Use the relation above.