Invoice templates

To make customized Invoices to bill customers for incoming calls through our PBX and Credit Notes to pay telephone agents for time worked. We make and supply interchangeable background images for the LibreOffice Calc Spreadsheets. We need 3 small spreadsheets with background images of "top - center and bottom part" of an invoice-template on the same page but the client only sees the whole invoice, he doesn't see the spreadsheet ! Min. knowledge: 1) LibreOffice Calc Spreadsheets. ( Asterisk PBX would help ) This is a none standard project and absolutely not for beginners !! Very good knowledge of the way LO Calc Spreadsheets work is needed. -- Good and quick communications are essential ! You must have a computer with a Linux OS --- This is not for Windows !! Please read and understand the file attached to this project, for instructions ! The cells of the 3 spreadsheets must all have their unique addresses for Asterisk call i/p.