Legacy PHP Web Development

I need to make modifications to a very old PHP app. It's an open source CRM project called PepperPM. My client needs modifications made to their contract form. It's legacy PHP and MySQL. I have a Dockerfile that you can use to run locally for development. This application is hosted onsite and I will support the deployment.

* Add/remove fields from contract form
* Add/remove fields in mysql
* Provide sql script to apply db changes
* Experience with Git