Download WP Move Users v1.4.0 – WordPress Plugin This kind of WordPress Plugin allows you to quickly move users from one WordPress site to another. Its WordPress Multisite ready so the plugin even works on entire networks.
List of Features
Export Users To export the users you have multiple options. You may export all users or choose to include or exclude specific users structured on user IDs.
Importance Users Once you released the users on the first site you now can just paste the export code that will transfer the users into the new site. If your running a Multisite network you will have the option to incorporate the users to a specific subsite, add them all to the key site or both to a subsite also to the key site.
Download WP Move Users v1.4.0 – WordPress Plugin
Demo & Source: DEMO