Have you tried with union in tableau, if you tried before then what is the result.
Please attach workbook.
I have read that Union only works between tables of the same data source, just like different tabs in Exce? I unfortunately cannot send you the workbook, since it is connected to data from a Company. Is there perhaps another Workaround?
I found this Problem a lot actually when it Comes to joining 2 different tables from 2 different data sources and both tables have different Dates. So data blending in this case will not help. In the end i have missing values.