How about a data blend? or are you looking for a parameter? and there are lots of other options depending on your situation. Can you provide some sample data or packaged workbook that represents your situation?
I am having a similar problem:
In the example Tableau workbook called Sales, there is a worksheet called something like Actual vs. Planned Sales. After I saw this worksheet, I wanted to create a similar one for my organization. The sheet uses an excel sheet for the second datasource, so that was my first step as well, however it turns out that by using an excel sheet you can only get the year target and I want the month targets as well.
So my next solution was to include the table in the original datasource, however when I do this Tableau connects the target to almost every data, this leads to a target of billions instead of millions. Furthermore the date variable can’t connect to the other date variables in my datasource.
How to solve this? -> SOLVED
(attached is the example workbook)
I don't see a sample workbook - can you please append? Thanks.