Dynamic range names based on pivot table fields?

Hi
Is there a way of creating a dynamic range name from the contents of a field in a pivot table.
I attach a simple example workbook which shows a pivot table based on some dummy data.
I'm trying to create lists for drop down boxes that update based on the user's selection.
I want the first drop down box to show the values in field "Ref 1", ie AAA, BBB and CCC. But these values need to update if the data in the table changes. I thought I should use a dynamic range name referencing the field "Ref 1", but can't seem to find a syntax that works.
Then, say if the user selects AAA from the first drop down box, then a second drop box would show only the valid fields from field Ref 2, ie DDD and EEE.
Then, ultimately I would want a third drop down box that shows only the valid fields from the pivot table based on the selections in drop down 1 and drop down 2?
Can anyone set me off in the right direction?
Thanks