Groups and Ladders

Ok, is there a way to do the following:

I have a group called Staff and I have a group called Students.

I want the Students group to start of with 1 star for under 40 posts, then 2 stars for more than 40 post but less than 150, 3 stars for 150 to 300 etc....

I want the Staff group to grow in the same manner...  but I want the staff group to stay in the staff group (only the stars change) and I want the students group to stay in the students group (only the stars change)...  how is this setup in group managment, or can it currently?  The forum is new to me, so maybe I am not understanding group managment.  If there is something already posted on this, please just point me too it....   Thanks!