Track db manual changes without reference db?

Hi,
I would like to achive the following workflow:
- developers have a local copy of production db
- developers change db manually during development
- when the changes are ready, developers should be able to produce easily a changelog and share it with everybody else.

I don't understand whether the changelog can be produced with respect to the "original" db structure, without the need of keeping and maintaining such original reference db.

In other words, can I run liquibase to compare current db against the original creation statements + any successive changelogs?

thanks