Report and a Form Filter

Experts, I have a report that uses a filter form:  "frmFilter_ShortByMonth"
I have a unbound combo:  "frmFilter_ShortByMonth.cboExecutiveOwner with a query as a row source:  
SELECT Import_Excel.ExecutiveOwner FROM Import_Excel GROUP BY Import_Excel.ExecutiveOwner;
The user selects a name from the cboExecutiveOwner then clicks the button and the report shows data for that selection.  

I now need to add functionality to show only records where the [ExecutiveOwner] is not null or "".
The user has to be able to do this has to be on the fly.  I know I can put the criteria within the query but I need it to be more dynamic.  

SELECT Import_Excel.*
FROM Import_Excel
WHERE (((Import_Excel.[Due Date per docs])>=[forms]![frmFilter_ShortByMonth]![txtDateFrom] And (Import_Excel.[Due Date per docs])<[forms]![frmFilter_ShortByMonth]![txtDateTo]+1) AND ((Import_Excel.Completed) Is Null) AND ((Import_Excel.ExecutiveOwner) Is Not Null And (Import_Excel.ExecutiveOwner)<>""));