Counting duplicate rows once under parent rows


I am trying to figure out how to count rows in a column that have duplicate entries only once. In my screen shot below, you can see under the "Action Area" column that a "Resident" can have multiple actions under the same action area. Here' it's "diet." But for each "Resident", I want to be able to count "diet" only once for each "Resident" in the parent row (not 5 times as with the first resident or 4 times as with the second resident). Is that possible? TIA!