If you don’t make backups, you’re doing it wrong! A comprehensive backup plan should be considered mandatory for any site with worthwhile content. This can become quite the process when dealing with data scattered over several domains, but a multisite network is an easy way to maintain live copies of a number of websites all in one place. An added benefit of these shadow sites is that they can be used as a testing ground for new features.
So what’s involved in creating a multisite network? Well, it’s mostly the same as a standard WordPress setup… mostly. Get a clean installation going somewhere (since this isn’t for the general public, it doesn’t need a domain name and should just be tied to a server or IP address). Then start things off by adding
define('WP_ALLOW_MULTISITE', true); to your wp-config file. From there, it’s only a matter of tailoring the Network Setup options to your environment.
Back that Data Up
Once the initial configuration is out of the way, you can start creating sites as an all-powerful Network Admin! Import data into them from your various domains, and be sure to block search engine traffic for each under Settings > Privacy to avoid any chance of being flagged for duplicate content.
It takes a bit of work at first to set this up, but when it’s done you’ll have a centralized, complete online copy of your websites including all the glorious text, media, categories, and tags that make them your own.