Hi Gurus,
Is there's a way to to a SUM (distinct) in a report?

Basically, say, I have this 2 column report that is group by a certain field.
I want to SUM the Parent column based on a distinct value and the Child column as per normal.
I can see that the build-in aggregate function has distinct on Count but not on Sum.

How will I achieve this?
thanks in advance.