You may edit the contents of this file in the same way as the other customisable pages, but this has the additional feature of allowing additional pages per site.
If you wish to add a site-specific page, create a subfolder beneath the folder containing this file. The name of that subfolder should just be the site number, and the folder should also contain a Content.html file similar to this one.
The URL to your site specific contact pages will be the same as this,
but with the addition of ?SiteID=n, where n
is the site number.