I have a table with a drop-down field (Item Code) that is initially populated by a lookup rule.  However, there's another lookup rule that will fill that table with records when the user selects from another drop-down (Similar Item Code) in the main body of the form.  Sometimes selecting a Similar Item Code will have no results to populate records in the table; in that situation, the Item Code drop-down needs to show a list of Item Codes that the user can choose from, but the drop-down is empty due to the Similar Item Code lookup rule having no results.  How can I keep the Item Code drop-down populated in this situation?