Your data lives wherever you decided to install the server, if you need to move the data the libraries use, I think moving the entire install should be the way to do it.
Seafile stores the data you upload to the server in its own format, that allows data integrity checks and accurate versioning (history) while having many clients making changes to the library, this is at the core of seafile and it is what makes it a robust solution. So no, you can’t tell seafile how it stores the data, this is a limitation but a virtue at the same time.
With this being said, if what you are looking for is a way to access the data in the libraries, in the same server, without needing to sync it and effectively duplicate it on the drive, there are some alternatives.
If you only need read access to the libraries, you can mount all the libraries on the server using the fuse extension.
If you need write access to the libraries, seadrive can be installed and configured on the server to connect to itself.