I think that Activities will have to be on your System sheet somehow in order for it to work.
That will cause there to be multiple squares for each System. Even so, I'm not sure that it's
going to be able to fully work.
There is alternative, but it may not be suitable for your datasource type or the size of your dataset.
It is joining the datasource to itself on the join field of Activity. This way, there is a row for each
System that shares an activity with another System.
Then System can be placed on both your Source Sheet and the Target Sheet
(which is a list of the Activities with their Systems next to it).
There is a further bit of trickiness involved in what to show when nothing is selected.
There are multiple copies because of the join, but the following simplifies it:
IF MIN([System Name])=Max([System Name])
AND FIRST()=0 THEN MIN([System Name])
ELSE MIN([System Name])
Please see the workbook attached in the Forum Thread.
270740filter_v10.5.twbx 167.3 KB
Thank you! I had suspected that this sort of operation wasn't supported; your alternative was very helpful.