I think what you're saying is you have 20 "Y" variables (i.e. columns), not 20 rows of data, right? And your problem is you have to do everything 20 times to apply updated data? There is a general trick to applying changes to all instances of reports within a report window when you are using something like a "By" variable or have multiple responses. That is to hold Ctrl when you click through the red-arrow menu. In your case, do what Jim suggested while holding the Ctrl key down.
In addition, if you save the script to the data table, you can you always reproduce the entire analysis with updated data just by running the script again.
-- Cameron Willden