Hi,
create a common include directory and put the include files into that directory (or subdirectories in that directory if you want to have some include file structure).
Then add that include directory to the include_path variable in php.ini and restart the web server.
It's not neccessary to have include files that are not requested directly with a browser somewhere inside document_root. I'd recommend to have a structure like e.g.
host_base\htdocs
=> html files, php scripts that are requested by a browser, images, css,....
host_base\include
=> include files needed by php scripts in htdocs, add host_base\include to include_path in php.ini
Example:
There are the files
host_base\include\myinclude.php
host_base\include\dir1\anotherinclude.php
host_base\htdocs\index.php
Just use e.g.
require_once 'myinclude.php';
require_once 'dir1/anotherinclude.php';
in host_base\htdocs\index.php
Thomas