1. In a timeframe comprised of a predetermined number of time periods, a dynamic fulfillment planning method, comprising the steps of: providing a baseline demand signal signifying a current fulfillment plan; providing an updated demand signal signifying desired changes to the current fulfillment plan; calculating, using the baseline demand signal and the updated demand signal, a cumulative exceeding demand signal signifying an amount of updated demand which cannot be completed within the current fulfillment plan; distributing the cumulative exceeding demand signal across the baseline demand signal according to a predetermined rule to create a normalized updated demand signal; calculating a new fulfillment plan using the normalized updated demand signal.