Managing version control of Erwin file changes with multiple environments

Question

What is the easiest way to manage three environments (DEV, QA and PROD) within a single Erwin file or multiple Erwin files? The Erwin file is separated by subject area, so I'm not sure reverse engineering is a viable option. We perform migrations every day, but they don't always conform to what is in Erwin, so we have a difficult time showing our end-users what is in QA and what is in PROD.