Deleting Duplicates From a Drop Down List That Refers to a Dynamic Range

[MayBTheresHope]

Hello,

I'm by no means proficient in Excel, so please be patient. I have been trying to find a solution to this problem for several hours and can't find an answer that specifically correlates to my needs. Here goes.

I created a workbook that will be used by others as trial template. The main page is a trial design sheet where the user can input codes and trial variables that are subsequently used elsewhere in the template. Each header column available for data input is set up as a defined name with coding to make it a dynamic list. The codes are obviously all different, but there may be some duplication of trial variables.

In other tabs, I have set up drop down menus that pull information from the dynamic lists in the trial design sheet. I want to be able to delete duplicates from the drop down menus. I know I can create a pivot table and do this, but I can't figure out how to make the pivot table dynamic and I know that the users will forget to refresh the table. Is there another way to do this? I've attached a dummy spreadsheet to illustrate.

Thanks in advance!
Sandy