Currently, if you are trying to share multiple content items from one group to another, there is no way to do this from within the group's content page. Our team recently tried to do this, as we needed to create a group with different settings, and we had to manually share all the content and track it to get it moved over to the other group. If there was an option in the content tab of a group to share the items to another group, it would be very helpful. This functionality is already available when managing content items from withing the Content section of Portal/AGOL.
