I have two columns, [Customer 1] and [Customer 2], they share 4 of the same members; 'Member A', 'Member B', 'Member C', and 'Member D'.
I have multiple charts on my sheet, some pertain to [Customer 1], some to [Customer 2].
Using a Filter Pane, I am trying to create a formula that shows only the 4 common members (A-D) and when one is selected, the filter applies to both [Customer 1] and [Customer 2].
It seems to me as though you need to alter your load script to include a link table which includes the common customer values and use the field from this table in your filter pane.
I'd probably agree with @rbartley. But this should give you what you want: this will only show where values exist in both customer fields and selects the value in both fields:
