This simple just placed “ALL” word in that Column where you put region name.so that you can get ALL word in selection list say B1. Now put Detination in one cell lets say “C1” Cell
and now put If Contion in D2 cell write IF(C1=“ALL”,Vlookup(B2,SourceDateSelection,Column,0),Vlookup(B2,SourceDateSelection,Column,0))
This forumla you need to extend upto no of Regions present in you sheet.
It depends on where your data is coming from. If you are using Query Browser to bring the data into your excel sheet, then you can pass all to a cell in your excel sheet from the drop down selector. The adjacent cell can be configured to display the #Div/0! error. When you pass that as an input value to your prompt in QB, it will bring back data for all regions. Obviously, your prompt has to configured as optional.