You can copy a stream to an additional location in the library. At the moment, it is not possible to bulk-copy items. Contact your admin if you can't copy a stream.
If you copy a stream from Your Library (limited access) to the Company Library (company access) or vice versa, the stream accessibility is impacted accordingly.
Select Conversations to access the Library.
Hover over the stream you want to copy and click
Select the destination location and click COPY.