I have configured OpenERP 7 to invoice from timesheet. Employees select a project task in their timesheet and an activity is automatically created. Invoices are created from timesheets but our customers need to know which Project tasks has been invoiced.

I would like to add the project name and tasks name in the printed invoice. What is the easiest way to configure OpenERP to do that ? Actually each line contain only the activity description which is always "/" because employees never populate that field.

Thank you