How do I approve the membership requests from people who have requested to join a limited- or private-visibility subgroup?
Unlike Groupsites, where you can approve membership requests, subgroups currently do not have this feature. If you set a subgroup to "Limited" visibility, a Groupsite member can request an invitation. The administrators of the subgroup will receive an email to this effect and if you wish to allow this person into the subgroup, you must send them an invitation through the subgroup.
How can I see Pending Members of my subgroups?
You can view a list of pending members (people that have been invited into a subgroup) from the Pending Members areas of your subgroup. Access this area by clicking on the "Invite Members" option from your subgroup menu:
Your invitations page will load and a "Pending Members" subtab will appear in the sub-navigation bar. Clicking this subtab defaults to a "Non-Members" view of your pending members:
Because you can invite both Groupsite members and non-members into the subgroup, you will also see a button for "Groupsite Members." Click this button to view pending members to your subgroup who are already members of your overall Groupsite:
Toggling between these buttons allows you to view both categories of pending members to your subgroup.