The Global Collaboration Framework includes an extension named BCGcfFolder that extends collaboration functionality to the folder level. When assigned to a folder type, it shows a Collaborating Shares property page for every folder created with that type. The property page allows users to select shares with which to collaborate on the entire contents of the folder.
When shares are selected for a folder:
You can register the BCGcfFolder extension as described in Registering the Meridian Enterprise extensions.