FrontAccounting PHP Modification Needed

I need to add couple simple changes into front account software, located at [login to view URL], which is a open source software in PHP. While creating Purchase Order I need an option to upload a .pdf file which will send out along with the Purchase once you are done with the PO it will take you to a second page where it asked you to email so I need a feature to allow uploading .pdf which can go along Purchase Order, please advise if you can do that. Thanks