Customize Multiple Sites Completely Separately

How to customize sites from the sites directory.

The following assumes you have already added the line $domains['mydomain.com'] = 'mydomain.com'; to /sites/bootstrap.php

app/Plugin/Contacts/View/Contacts/index.ctp Is the view file used by default when you visit "mydomain.com/contacts/"
If you would like to create your own view file then in /sites/mydomain.com/Config/core.php set the language setting to : Configure::write('Config.language', 'en');
You can then create a substitute view by adding the following file... /sites/mydomain.com/View/locale/en/Plugin/Contacts/Contacts/index.ctp and customize the view as you see fit.

If instead of a single view you need to update the entire contacts plugin rather than just a view, you would begin by...

copying... /app/Plugin/Contacts
to... /sites/mydomain.com/Plugin/Contacts
You can then customize the controllers, models, views, etc and completely bypass the core app for this single plugin, on this single site (mydomain.com). While all other the sites that use this install will still make use of the main default app/Plugin/Contacts plugin.