Sara,
I'm trying to understand more of your usage case. Is there a reason for having 160 groups? Groups are meant for configuration, so if you can condense the 160 without using global groups, that may be better. If you're trying to partition the groups for viewing, then you may be thinking of folders.
With folders, you can have a Top folder that encompasses everything with several subfolders. And then the subfolders can have additional subfolders. The concept of subfolders is not there for groups.