You may create (‘embed’) a shared workspace inside a workspace using Access Invite Member or Access Public Access from a folder entry’s action menu, using the respective File menu options in the folder’s top menu.
You may also embed a workspace in another by transferring a workspace to another via cut and paste. The members of the new higher-level workspace (its member group) are automatically added to the members of the embedded workspace, and the members of the old higher-level workspace (if any) are removed from the members of the embedded workspace: embedding a workspace in another automatically changes the membership of the workspace that you transfer. Remember to check whether these automatic changes are what you intended and correct the membership and the access rights if necessary.