your insert form should insert the case data to the case table, then in another insert behavior, it can insert the case ID using the session that is created from the first insert to the files table and use the Server File Name binding from the WA Uploaded Files binding group to insert the file name to the files table. 
Hi Jason, yes I managed to finally work it out early this morning by playing around. What threw me was DFP doesn't create the insert behaviour, its little things like that which keep me on one page for days!
Now I need to work out how to retrieve the doc in the detail pages, another head scratcher for me I am sure!


