Question [GroupManager] is it possible to make a max amount of players in a group/rank?

I'm running a 1.8 Bukkit server (Home hosted for testing) and i have a system where i limit the amount of people who can be staff, for example: Helper has a max of 5 players, Admin has a max of 4, etc
I cant find a way to actually set a max amount. I just keep track of it myself.
I'd like to know if it is possible to make a max amount of players in a group.
Because i don't want too much staff, and too many people in one rank.
Like if i were to try to add someone to a rank that was full, it would return with: "Sorry, This rank is full and no one else can be added to it" or something like that.
Is there an option/command/PermNode within GroupManager to do this? If not they should add it, I think it would be a pretty good system.
Is there a plugin that allows me to do this?
I've done google searches and can't find anything about this.
Also, I can program but i don't know how to do JS only C#.. So any code you provide, Please explain where to put it etc.
Thanks to anyone who can help.