Your main domain will point to public_html
When you use the "add-on" feature, the add-on domain will point to a subdirectory of public_html
You can have up to 3 add-on domains, for a total of 4 domains with separate information.
So, main.com will point to public_html
son.com can point to public_html/son
daughter.com can point to public_html/daughter
mistress.com can point to public_html/mistress
Note that the system default is to make the subdirectory the same name as the domain. ie if you add google.co.cc , the default directory will be public_html/google.co.cc . You can change the default when you create the add-on
To make sure that they do not access son.com/index.html via main.com/son/index.html , you have to adjust the .htaccess file.