We need a little guidance when trying to change a sales transaction detail from an external application to our CRM 3.0 server. In R/3 we used to be able to pass the order number in as the key. With CRM the GUID is the key. If the external application does not know the GUID then how do we get it in order to read and change the details using a BAPI like BAPI_SLSTRANSACT_CHANGEMULTI?
i.e. We want to enter a customer number or date range to return orders and then double click the orders to get the detail in order to change it. Any ideas as to the sequence of BAPI calls that are required to achieve this?