The CONFIG Item created (when 'Autocreate Config Item" program runs) is Shippable and has all information inherited from TOP MODEL. This is the one that is tied to deliveries and should be sent via EDI 856. Please check and let me know which specific data item are you missing.
For ATO Models and PTO Models, you can get the top model item by using the TOP_MODEL_LINE_ID column in OE_ORDER_LINES. For PTO Kits, there should be a similar flag that links the exploded components to the KIT item (possibily LINK_TO_LINE_ID would provide the join you are looking for)