Thanks Diego, much appreciated.
The issue is a bit more complex because the process involves transfering the information from a form type (e.g. 139 = Sales Order) into another form type (e.g. 179 = Sales Credit).
As per my understanding (please correct me if I am wrong), if you save a document as 'draft', you can only open it as a document of that type (e.g. Sales Order drafts are open as Sales Orders).
Best regards.
N