dovecot - Jun 2019 - Authentication against multiple mysql databases

Hello,

I have setup authorisation against a mysql database.

I'd now like to do (additional) authentication against another mysql
database.
i.e. I have two databases with usernames and passwords and I'd like allow
all
the users from both databases to be able to login to IMAP.

Can I simply extend 10-auth.conf in conf.d with additional !include files - like
auth-sql.db1.conf.ext
auth-sql.db2.conf.ext
and associated filed etc.

Or do I have to create a new database and set up a view onto the other two 
databases / tables?

Any ideas?

Thanks,
-Graham-