running a hypothetical for pre-testing

one of our clients asked what it would look like if they stopped doing 3%NE SH-if there would be refunds/ how much. Is the simplest solution setting up a new plan and uploading the census and running the tests? I know what I'd do in Datair, but that's not an option right now. 

Are you using the FT William system?  I see ftwilliam.com in the date and time.  Is there a downside to loading preliminary census data into the existing plan and running an ADP test?  If it is FT you can modify the plan provisions then just switch them back after you get all your reports.

Of course if it is FT you can always call them and get their advice; probably the safer course of action.

Can  you do it in a spreadsheet?