You can add users and groups to other groups. This relationship isn't one-to-one, so you can add the same users and groups to multiple groups.
How to add users and groups to other groups:
- Go to Partner Center > Fulfillment > Users
- Click Groups
- Click on the menu (3 dots) > Edit group next to the group you wish to add users or other groups
- Click on the Users fields to add or remove users or groups
- Click Edit group