project_root/sites/example.com project_root/sites/example.com.a project_root/sites/example.com.b project_root/sites/example.com.a.123 project_root/sites/exa

project_root/sites/example.com project_root/sites/example.com.a project_root/sites/example.com.b project_root/sites/example.com.a.123 project_root/sites/example.com.a.234 Create these directories. Add a settings.php file to each. Add stuff to sites.php if needed. example.com.a and example.com.b should definitely work. Not too sure about the other two because I haven't created a site in a multi-site setup that is 2 subdirs deep, but it is easy enough to try. You may also need to symlink the subdirectories (e.g. a) in project_root. See "Subdirectory multi-site" here: https://www.drupal.org/documentation/install/multi-site https://www.drupal.org/documentation/install/multi-site