We have several projects working with the same database (different tables of course). It is possible to have unique databasechangelog and databasechangeloglock tables for each project? That would make it easy to deploy/rollback a separate project.
The Java API allows you to set the databasechangelog and databasechangeloglock table names on the Database object, but it looks like only the Ant task currently exposes that functionality.
Are you using Ant? Otherwise you can potentially set it yourself some different ways, but it doesn’t look like it supports it out of the box.
If you use different liquibase tables for each project, they won’t care they are on the same databases.