Dynamically interrupt News RSS feeds with Oranization specific messages

This would be a hybrid of a News RSS and Custom Messaging feed.

The idea being that the customer could drop in a local On-The-Fly message to all employees in the office, and the ticker would then fall back to the News feed from the BBC. 

A big factor of this would be the on-the-fly nature of it. Being able to update it immediately and have it switch back at  a certain time.

Perhaps through scheduling of multiple feeds?