Need help changing canvas size in adobe fireworks while having a master page set

I set the header,nav and footer on a master page in adobe fireworks for a website i am mocking up. The issue is that some pages have more content than others but since i have a master page set at a certain height and width then each page is the same size. I tried to change a page canvas size and then i notice my footer and other items disappear so it won't let me change a specific canvas size. Anyone know how?