Table from several datasources

Hello,

I am trying to create sell-out dashboard from several different data sources. (each data source = 1 customer).  

Data sources has database structure, but the structure is not always exactly same. (Cleaned in Power Pivot).

From the data sources I need few important information: Product code, month, year, sell out quantity. (all of the data sources has this information).

Then I have on source with conversion table, which converts product code into category, description, etc – so I use parameter “product code” to create relationship between tables.

As I already used 1 parameter to merge the sources - then I can´t make a table in the dashboard, with “product code” in the row and “sell out quantity” in the columns from all of the customers as it only count “sell out quantity” from only 1 selected customer.  

Does someone has any idea, how to create the table with sell out data from all customers?

Thank you a lot,

Jan N.