>What do you thing of using the average of the two >outputs (ex a level controller and a ratio >controller output) to act
>has the setpoint of a flow controller.
I would have to know more about the loop and its purpose. Such a scheme could serve as a form of feed forward, with the ratio controller output being the feedforward part and the level being the feed back part. This is somewhat like a 3 element drum level control in a boiler. In that rather standard control the seam flow serves as the setpoint (not really with a ratio, but one could be used) for the feedwater flow loop with the drum level serving as the feedback.