Dropdown List Always Shows Unique Values From Column Based On Lookup Value

I have a worksheet (say, Sheet1) that I am going to manually import a large data set into on a weekly basis for reporting purposes. One of the columns from this data dump will have the header "Design Id" in the first row, but it may not be in the same column every time. I am trying to figure out how to create dropdown lists on a separate worksheet (say, Sheet2) in the same workbook where the data source always looks up the column containing the header "Design Id" from Sheet1 and then returns only the unique values from that column as options in the list.