If you want to specifically exclude the outliers for that view for AB1 forever, you might create a filter that filters out just those points. One way to do that would be to make a combined field of all dimensions in question (group name, S, Set, Iteration, and Prefix) and filter out those combined values.
This method is option 1 in the following Knowledge Base article Hide Only One Instance of Sub-Category column
If you want a more ad-hoc solution that's quicker to set up, then you might just consider removing the exclusion filter when you change the value of prefix.
Hope this helps
Thank you Esther, that's a clever solution and will work for my purposes.