PHP application modification

We have a time tracker application for lawyers to track their hours, with a module for filing and reporting for the admin team. The developer who developed this project is not available and we need to make some modifications to it. The communication would be through Skype and we will show you the software via screen sharing. the application is divided into 2 parts. one for lawyers and other for admins. The lawyers entered the work they do, and the amount of time of that work, and the admins issue invoices, and create some reports regarding invoicing and productivity of the office. There is also dissburresments that are added to the invoices there are two types of invoices, Fixed fees, and by rate. the first problem I have is that when we issue the fixed fees invoice , we don't have the ability to enter the dissburresments as we can do to the other by rate invoice. This feature was not in the ap[plication and we want to add it. also, we need to issue invoices in different currencies, we only able to issue them in us $,take in coonsideration the rates of the lawyers are entered in US $ . We need to change some of the format in the invoice, and we need to adjust the final amount in the invoice to be approximated. we also need to generate some reports from the application