Programming is just driving your thoughts :)
So what i want to say that your question is how you can include just some part of an included file and my answer is that you can achieve that by doing a test each time the main file is included from withing this file to see if the file is included internally or not and you can be more precise in a way that you split your main file into block which are loaded due suitable variable
Take a look for this workaround and hope you will understand what i mean
Supposing we have the main file named main.php contains that contents
<?php
echo 'I am a java programmer';
echo 'I know also PHP very well';
echo 'When the jquery is my preferred toast !';
?>
now i have three external files that will include that file each file is specific for one of this 3 programming language
So i will create my 3 files in this way :
File : java.php
<?php
$iamjavadevelopper = 1;
include_once("main.php");
?>
File : phpfav.php
<?php
$iamphpdevelopper = 1;
include_once("main.php");
?>
File : jquery.php
<?php
$iamjquerydevelopper = 1;
include_once("main.php");
?>
and my main.php will be coded in this way
<?php
if(isset($iamjavadevelopper))
echo 'I am a java programmer';
if(isset($iamphpdevelopper))
echo 'I know also PHP very well';
if(isset($iamjquerydevelopper))
echo 'When the jquery is my preferred toast !';
?>
By this way each one of our three external files will show just a part of the included file :)
Hope that was clear and helpfull :) Any help needed i am just ready :)