How to filter EpiRetrieverCombo E9

Hello group. How do I filter the data in an epiretrivercombo? I have table ud01 populated with people. I have checkbox01 thru 04 for specific attributes. I would like to limit what the retriever displays in the drop list based on values in the checkboxes. For example checkbox01 is for inactive and will be used in conjunction with another checkbox. If checkbox01 not true and checkbox02 true then display.
I see the other combo objects have a filter property but not the retriever?
Mark D