I'd like to apply some additional criteria to this unique value count.

=SUM(IF(FREQUENCY(IF(C:C=A5,D:D),D:D),1))

The array formula works ok without additional criteria. However, I'd also
like to include the rows where cells in E:E equal 5 and F:F equal 4. I've
done a SUMPRODUCT that would determine that without determining the unique
values, but I want to somehow combine the two.

Any ideas.
Paul