Report Designer - Insights - Metric Filters

Does anyone know if you can use a list as a metric filter when editing an insight? Or alternatively, if you can't filter constituents and donors by lists, can you filter by constituent relationships? Or can you filter by a constituency code that isn't primary?

Ultimately what I'm looking to do is to build a dashboard for overall and grade level parent participation rates with individual insights for each grade level. I have a basic insight for donors versus constituents with primary code equals parents but if a parent happens to be a board member (which is the primary code) then they aren't included. And it also doesn't let me see the more detailed view of parent participation rates for 6th grade parents versus 5th grade parents because I can't filter by relationships or even by a static list of 6th grade parents.

Am I missing something obvious?