Add Shipping Fields to Magento Checkout Form

Hello, I have an extension installed on our Magento website named FastCheckout. In addition to the billing address, we need the checkout form to have an option for users to fill out a shipping address if it is different than the billing address. If the user does fill out a different shipping address then it needs to be reflected in the emails, orders, invoices, etc... Thanks Nils Satterstrom