Here's the backend tables (g sheets). Just 3 tables… items, centers, and item center. I use data validation of course. Tableau does the join for me.

https://docs.google.com/spreadsheets/d/1-85PV3YcnjBfIKhvyA6WfigI6sjvArsAsoBrXMSg9nw/edit#gid=1818969020