Variations

Hi, everybody! I developed a progress base for tracking monthly progress and calculating the actual proress achieved on a monthly basis. Monthly different variations and change orders are coming due to the design changes or some inaccuracies in the original WBS (which was taken as a basis for the progress base) prepared during the tendering process. How do you normally deal with them? Do you change the weightings each time the variation appear to reflect accurately the full scope or say incorporate the variation into the progress calculatio file if it a significant variation?