Reinstall multi-site in three domains

Hello

I am on installation process with this scenario:

3 domains, x.com, y.com, z.com

A multi-site network was creatod using x.com as primary domain.

The plugin “WordPress MU Domain Mapping” is installed to manage the domains.

This installation is wrong. I want to reinstall the multi-site network, and if it is possible, choose y.com as primary domain (x.com is the primary domain).

All domains has got information and are public webs, as it would be usefull don’t delete any database in the process.

Any ideas to get started?

Edit:

The wp-config of x.com (primary domain is)

define(‘WP_ALLOW_MULTISITE’, true);
define(‘MULTISITE’, true);
define(‘SUBDOMAIN_INSTALL’, true);
define(‘DOMAIN_CURRENT_SITE’, ‘x.com’);
define(‘PATH_CURRENT_SITE’, ‘/’);
define(‘SITE_ID_CURRENT_SITE’, 1);
define(‘BLOG_ID_CURRENT_SITE’, 1);
define( ‘SUNRISE’, ‘on’ );