The function to merge announcements allows for one course to push out announcements to other courses.

For example, a Nursing Program might include twenty different clinical groups.  By merging announcements, a single Nursing Program Master course site could be used to push announcements out to all twenty of the Nursing Program clinicals.  Announcements that are merged from the Master course cannot be edited or deleted in the other courses where they display.  Each of the clincal instructors could create additional announcements that would apply to their specific course only.  Those would appear on their own course site in addition to the announcements merged from the Master Course.