Inverse Aggregator
This measure computes the aggregation of the specified value but inverts a slicer selection on the specified category. In other words, instead of returning the SUM, COUNT or other aggregation of what...
So, the real issue you are having sounds like that you want to see a table with the non-selected names (categories in the inverse aggregator example). In other words, unlike the inverse aggregator which shows a table of just the selected values, you want to show a table of the non-selected values from the slicer. Correct?
The ugly part with my solution, if new clients are added, I need to regenerate the groups. If there is another way to make this dynamic as new clients get added, that would be awesome.