This can be easily done with a calculation field and a Let ( ) function. You will need a checkbox field for each field (or set of fields) you wish to switch on/off. You could also do this with only one checkbox field and a value list.
See the attached file for one way to do it...
Thanks for your reply, and example. That's really helpful. I see that the results of what is selected from the "include" click list is displayed in new box on the top right of the "registrar" tab. When I click "day 4" tab and click "Mailing List" it still generates the mailing list report with all the data, not just that which is selected on the "include" click list. Do you know how to link that?