Change of HTML inside plugins - child plugin?

Hello.
I jsut have started working with Shapely. It is first BS theme I use at WP.

I have a question. I wisht to change stuff in PHP, like this:
$class3 = ( ( 'background-full' == $instance['image_pos'] ) || ( 'background-small' == $instance['image_pos'] ) ) ? 'col-md-8 col-md-offset-2 col-sm-10 col-sm-offset-1 text-center' : ''

Because I need to change the BS clasess to something else.
Now, I have a child theme, but my child theme does change only my CSS. :

<?php
/**
 * Created by PhpStorm.
 * User: ragulin
 * Date: 27.09.2018
 * Time: 18:01
 */

//add_action( 'wp_enqueue_scripts', 'my_theme_enqueue_styles' );
add_action( 'wp_enqueue_scripts', 'func_enqueue_child_styles', 99);
function func_enqueue_child_styles() {
	wp_enqueue_style( 'parent-style', get_template_directory_uri() . '/style.css' );
	wp_dequeue_style('shapely-style');
	wp_enqueue_style( 'shapely-style',
		get_stylesheet_directory_uri() . '/style.css',
		array('parent-style')
	);
}
?>

If I change soemthing in directory wp-content/plugins/shapely-companion/inc/widgets/class-shapely-home-paralax.php , the change will be lost with next update of the parent theme.

How to change the “HTML” clasess or PHP itself corectly?

Thanks for advice.

Hey there

Thank you for your question,
Unfortunately, I’m sorry to say but such changes are not supported by default, modification in the core functionality in the theme files cannot be supported, sorry once again and hope you understand

If you put out update of theme, is there some documentation, which shows changes in code, which were made, so I can pick only safety updates, and ignore changes in styles and etc?

HI there

You can check our GitHub repo to see changes in the theme: