Is it possible, when using gradebook and og gradebook, to have a single group per group of students (like a homeroom group), but not make a separate group for each of their subjects (math, science, etc.)?

I'm trying to make use of gradebook's tie-in to taxonomy to avoid having to make a group for every class at the same level. For example, in grade eight, I want to create grade books for art, English, math, science, etc. But I am trying to avoid having to have a separate group for each of them (yes, teachers will have to work in the same groups).

So, I have groups for each grade level (there is only one class per grade or year), but if there were more, I would make groups for them, too. But for classes within that grade or year-group, I just have gradebooks.

I thought it was working, but now students from one level (e.g. eighth grade) are showing up in the gradebook of another (e.g. sixth grade). Do I have to have a separate group + gradebook for each class or course?