PHP/MySQL based inventory/asset/order management system

I have a bid out for a project to update an existing business database system, currently written in Java/JavaScript with a MySQL backend that is going to be needing some new additions made. The current system was originally designed for a manufacturing company which didn't require tracking materials per job, breaking out a bill of materials for items ordered, or several other tasks that their new "sister company" (a production company) now has to address. The new additions will require interacting with the existing user credentials system and have to work around the existing database structure. New table can be added, but significant changes to the existing database structure would need to be looked at on a case by case basis. We would like to make these new additions using PHP/Javascript as there is less issue with system requirements then (Tomcat isn't necessary as an example). Eventually the existing forms would most likely be rewritten for both companies using PHP, but for now we are focusing on the new requirements.