Change cell from dropdown list and clear other cells in row

Thanks in advance for your help.

I have dependent drop down lists in columns D,E and F. If someone changes any cell in these columns (D,E, or F) then I would like the other two cells to clear their contents so they then have to repick from the dependent list that matches that data chosen.

Example - if they change E4, then D4 and F4 go blank. Or, if they change F4, then D4 and E4 go blank. And the same thing if D4 is changed, E4 and F4 go blank.

The data for this worksheet begins at row 4 and at present time ends at row 6004.

Thanks,
Dale

It would be easier to offer suggestions if you uploaded a sample file