Add functionality to an existing PHP program

I work with a NGO that helps deaf children learn business skills. As part of the program, they make bags from waste fabric. Each bag is tracked on a database. When a customer purchases a bag, they can search for the bag number on the database, and see who made their bag, and how much of their money goes to the different people who made the bag. The customer can also used the same program to see how much money was made for a set of bags,and how the money was [login to view URL] software is written in PHP. The problem here is that I hard coded the way in which the money is shared for the different work done, as a result I cannot change the way money is given if a student graduates and wants to work from home, or if I hired a teacher and want to pay the teacher a salary instead of a profit share, of if the team decided to create a new role for managing donors. So, I need help with rewriting the PHP code, so it reads how the profit should be shared for the particular bag from a database table, and then calculates how the profit is to be distributed, and for what work. The current system can be viewed at: [login to view URL]