You need to add the standard E9 tables into the BAQ then use these fields in the display...E.G:
You have created a SQL view of customer orders which contains the CustNum field; in the BAQ designer get the external view then add in the standard e9 customer table (dbo.Customer) - create the joins yourself (as E9 cant do this for an external view) then in the display tab use the Customer.CustID field. This will enable the standard E9 right click functionality
Regards
Sue