Customization to add Invoice number to Monthly Sales Analysis

Customization to add Invoice number to Monthly Sales Analysis as details for all the sales sources as I was unable to find the invoice no field at the Report design field list. Client also required to show Invoice number as a detail at 'Sales analysis by Document's Reports. both cannot be done… as both report is show Sales Summary only.. How about use Invoice Listing Report ? Got it, I will check with the client to see if they accept the invoice listing reports.