Union tables in query

Dear Friends,

Could you give me some guidence about how to union tables in SQ02?

I put the table MSSL into "Alias tables",  but no use here.

Now I want to make  query to list the stock and value of packaging materials.

I use the table MARD as the basic stock table, MBEW to find the price and MVKE to ensure packaging materials.

But we want vendor stock also. Could you help to to add table MSSL into the list?

Thank you very much!

Best regards,

Peter