Trying to use sale_complaint module, I didn’t find how to fill a complaint. On http://demo5.0.tryton.org I created a complaint type : “Missing item” with Origin=Invoice Line.
I go to Sales and complete a sale for customer Cooper’s Seafood House (invoice posted, shipment done).
Then on a new complaint form, I choose Customer=Cooper’s Seafood House ; Type=Missing item. After choosing in the list for Origin the item “Invoice Line”, this entry disappear and is no more available ; I see no way to select the invoice line concerned by the complaint.