I am working on a reporting scenario where I need to query multiple databases (for the same product) and show it in a single dashboard. The dashboard is on SSRS.

Connecting to multiple databases is not a challenge.

How can I be able to do an union of the two datasets on SSRS? I need to show some grouping and charts etc on the merged data. The merging is basically just UNION.

I was reading DPE (http://msdn.microsoft.com/en-us/library/ms152816%28v=sql.105%29.aspx). If I get some clue, I can start on this.