Add the ability to share content across different groups. That way, only one current version of the content is needed, and can be easily updated and versioned as needed.
But to the end user the content displays as it is hosted in the group, with the same user experience, same preview and same download features as other content saved within that group. Bit that same content may be displaying in several groups sharing that same content.
Where it is hosted and how it is downloaded is transparent to the end-user.
Other similar platforms have this feature built in