There are several questions on SO about version control for SQL and lots of resources on the web, but I can\'t find something that quite covers what I\'m trying to do.
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You've got quite a rigorous set of requirements, I'm not sure whether you'll find something that puts checks in all the boxes, especially the multiple concurrent schemas and the intelligent version control.
The most promising tool that I've read about that kind of fits is Liquibase.
Here are some additional links: