In a School Form's Settings > Recipients > Add dialog:

when Recipient=User, Regarding is going to be parents, 

Role=Parent as a filter, Grade= anything but "select an option", click search icon

then results=0.

I cannot just add 10th Grade Parents therefore. Nor K-8th Grade parents, etc. (Need School Division filter really; a different enhancement.)

We can only add all Parents (click search when only Role=Parents is set), or find individual parents by typing text in search box as well. Nothing in between.  A couple of our forms are just directed toward a subset of parents; don't always want them regarding students.