Each site has its own scope of content. Additionally:
- a site administrator should be able to display content from any of its sub-sites
- a site administrator can specify whether child sites can display content from the current site.
Displaying content from parent sites or sub-sites will be done through the Asset Publisher portlet. (When the portlet is configured to link content to its own page/context, then clicking it would take the user to the site where the content belongs to.)