Multisite subdomain microsite on secondary domain

After you create the sub-site, go into the Site Settings (via the Network Admin) and change the URL for the sub-site to .

That’s the same way that you would assign another domain name to a sub-site. For example, if the main site is, sub-site 1 would be (you decided the subfolder name). That is what you use when you create it.

Then change to . Since your hosting nameservers know about ‘’, that shouldn’t require any additional configuration changes at the hosting level.