We have two different WordPress websites for our clients. Both have different content that need to be on separate installations. One installation already has all of our users since it existed well before our new site. Is it possible to authenticate the new site through the old one?
I've seen plugins like this:
https://wordpress.org/plugins/external-db-auth-reloaded/
But that is for an external Non-WordPress database, so none of their information will carry over.