Nested groups and invites by selection of username instead of manually typing

Hi all,

Is there a possibility for group nesting in Organic Groups within Drupal Commons?

For example:

Students --> Regular students & Work students

My second question is if there is a module available that simplefies the membership of (Private an Invite only groups). Standard we have to manually type in the name, a list with checkboxes would be great!

Thanks in advance!

Kim