In a free Groupsite, you are allowed 5 subgroups. These 5 subgroups can only be created by a group Manager. With the unlimited subgroup premium feature, you can have as many subgroups as you wish and you can control if these groups can only be created by a manager or if you can allow all members to create subgroups.
Here's how to control that permission:
1. Select the MANAGER tab, then from the "Group Settings" page select "Subgroup Controls"
2. On the "Subgroup Controls" page under "Subgroup Settings" you will have Premium Options which allow you to select to allow "only managers" to create subgroups or "all members". Make your selection then hit UPDATE.
3. You can also decide who can invite members to the Groupsite. If this is set to "only managers", then subgroup members can invite other existing Groupsite members to join the subgroup but will not be able to invite people who are not already in the overall Groupsite.
By changing this option to allow "all members", members can invite anyone to the subgroup which requires them to also be invited to the Groupsite at the same time.
Here is more on inviting to subgroups.
