With the upgrade comes new functionality. In playing around, I found this new piece that may be helpful to members of this community.
When you have a private group, you may share share content with users outside of this private group. (This does not work for secret groups or forums.)
To do this within a group, go to Manage, then Settings:
Select on "About"
Then under "Extend Visibility", check the box next to "Non-Member Content Editing".
From this point, when you attempt to share content with a user who is not a member of the group, you will see this menu.
Any member of the group can see for each document who has access outside of the group and revoke that access.