After looking for this answer, I found a lot of things that looks like this, but it are the same. So here we go. :)
I have a large blog running. Thousands of posts, a very specific category structure, very specific template and a permalink structure that is like: domain.com/category/slug.
Now I am about to start a rebranding of my site, starting with the installation, categories AND the permalink structure -- that I want it to be domain.com/slug-id.
I'm comfortable with the idea of multiple installations, multiple databases. As a matter of fact, I would never touch the "old" one database again, so that's perfectly fine. It would be also ok I moved this old installation to a new folder.
BUT I'd like to keep the permalink structure for this old installation and start this different one with the new installation.
Is it possible? If so, can you guide me how to? :)