Wordpress Multisite and CiviCRM with multiple databases
Well, the answer appears to be 'Yes, it is (almost) that simple'.

The one wrinkle is that you first need to trick CiviCRM into thinking it has not already been installed on another Wordpress network site by moving civicrm.settings.php to an out of the way location.

So, do this:


Move your old civicrm.settings.php file somewhere safe.
Create a new empty MySQL database.
Go to the Wordpress site where you intend to create the new CiviCRM instance and activate the CiviCRM plugin.
CiviCRM will go through the process of installing CiviCRM to the blank database.
A new civicrm.settings.php file will have been created probably in a path like: /path/to/wordpress/wp-content/uploads/sites/2/civicrm/civicrm.settings.php
Restore your old civicrm.settings.php to its original location (in my case this was in /path/to/wordpress/wp-content/plugins/civicrm/ because it's an older install).


The 'old' settings file was edited something like this:

&lt;?php

$site = $_SERVER['SERVER_NAME'] == 'newsite.com' ? 'new' : 'default';

if ($site != 'default'):
    include_once('/path/to/wordpress/wp-content/uploads/sites/2/civicrm/civicrm.settings.php');
else:
    /*The contents of the old original settings file goes here.*/
endif;

?&gt;