How do I take an Aggregate Measures from one data source and use it in a sheet from a different data source and not  have it aggregate there?

Denise,

I am confident that what you want to accomplish can be done in Tableau, but in order to provide assistance, you will need to provide additional details on your situation. A packaged workbook, a .twbx file, that represents your situation and details on the logic you would like to apply, and the results that you want from your sample data would enable assistance.