I believe I understand your problem and what you are trying to do, would it be possible for you to share an example workbook?
How we go about this can depend on the structure of your data, so I don't want to give you incorrect answers.
Hey Cody Lester, welcome to the world of Tableau!
My advice would be to create a separate worksheet with the projected column and then put both worksheets side-by-side on a dashboard. I use this at work to make it look like they're all part of the same dashboard.
Just for future reference, attaching a packaged workbook can help people better answer your questions by showing you how to do it rather than just telling you . You can make a packaged workbook by clicking File -> Export Packaged Workbook.
I'm not opposed to using workbooks side by side in a dashboard to get what I need as long as it works.
Tableau help.twbx 3.7 MB