I have created a group and then tried to create libraries as that group so that the group is the owner of these libraries. Unfortunately, it seems that it is not possible for a group to be the owner of libraries, and they can only be owned by an individual. The consequences of this is that when I make other users administrators of the group, they do not implicitly have the ability to share these libraries with other people. Only I, as the owner of the library can do this. It appears the the only thing group admins can do is add other members to the membership of the group which is fairly limited.
Would it be possible to have groups be the owners of libraries, so that administrators of the group have the admin capabilities that come with owning a library. Obviously libraries shared by an individual with a group, should still only be administrable by the individual owner of those libraries.