After you refresh, you should see both tables in your pivot table field list. Once you create the list as a separate table, add it to your data model and link the 'Sections' field from the original Data table to the 'Sections' field in your new table.
In this case, it would be a unique list of 'Sections'. I was able accomplish something similar by creating a separate table containing a unique list of the values I wanted to remain static in my pivot table structure.
