Sending a newsletter to multiple Organic Groups (is this possible?)

Hi all,

I have a school website that I run. There's an organic group for each grade. What I now need to do is send a newsletter out to a group of groups. Example:

Middle School Newsletter goes to:

OG Grade 7
OG Grade 8
OG Grade 9

High School Newsletter goes to:

OG Grade 10
OG Grade 11
OG Grade 12

Is there a way to do this? Any ideas??

Thanks...