How to display customer item and Oracle inventory item on same line

 I wanted to understand how other Oracle shops are using O/M.

My users often enter a customer item or another type of cross reference item which displays in the ordered item field.  We also want to display the actual item from mtl_system_items  (it exists since inventory_item_id) is filled in.

Can this be done using standard O/M functionality or is a customization required-- and what would be recommended?