Unsure how to hook functions in child functions.php

Hi all,

The current theme that I am using is Interface (free) by theme horse. I am trying to edit some code in the header-extensions.php file. In the directory of the parent theme, it is located in interface/inc.structure. I created a copy of the header-extensions.php file in my child theme directory in interface-child/inc/structure. Any edits I make to the child theme header-extensions.php file are not applying.

From what I understand from my research I need to unhook the function in the parent functions.php file that loads the file from parent directory. The parent functions.php code is the following:

function interface_load_files() {
	/**
	 * interface_add_files hook
	 *
	 * Adding other addtional files if needed.
	 */
	do_action( 'interface_add_files' );

	/** Load functions */
	require_once( INTERFACE_FUNCTIONS_DIR . '/i18n.php' );
	require_once( INTERFACE_FUNCTIONS_DIR . '/custom-header.php' );
	require_once( INTERFACE_FUNCTIONS_DIR . '/functions.php' );
	require_once( INTERFACE_FUNCTIONS_DIR . '/custom-style.php' );
	require_once( INTERFACE_ADMIN_DIR . '/interface-themedefaults-value.php' );
	require_once( INTERFACE_ADMIN_DIR . '/theme-option.php' );
	require_once( INTERFACE_ADMIN_DIR . '/interface-metaboxes.php' );

	/** Load Shortcodes */
	require_once( INTERFACE_SHORTCODES_DIR . '/interface-footer_info.php' );

	/** Load Structure */
	require_once( INTERFACE_STRUCTURE_DIR . '/header-extensions.php' );
	require_once( INTERFACE_STRUCTURE_DIR . '/searchform-extensions.php' );
	require_once( INTERFACE_STRUCTURE_DIR . '/sidebar-extensions.php' );
	require_once( INTERFACE_STRUCTURE_DIR . '/footer-extensions.php' );
	require_once( INTERFACE_STRUCTURE_DIR . '/content-extensions.php' );

	/** Load Widgets and Widgetized Area */
	require_once( INTERFACE_WIDGETS_DIR . '/interface_widgets.php' );
}

The code in my child functions.php file is the following:

<?php

function unhook_thematic_functions(){
	remove_action('interface_init', 'interface_load_files', 15);
}

add_action('init', 	'unhook_thematic_functions');

add_action( 'interface_init', 'interface_child_load_files', 15 );

function interface_child_load_files() {
	/**
	 * interface_add_files hook
	 *
	 * Adding other addtional files if needed.
	 */
	do_action( 'interface_add_files' );

	/** Load functions */
	require_once( INTERFACE_FUNCTIONS_DIR . '/i18n.php' );
	require_once( INTERFACE_FUNCTIONS_DIR . '/custom-header.php' );
	require_once( INTERFACE_FUNCTIONS_DIR . '/functions.php' );
	require_once( INTERFACE_FUNCTIONS_DIR . '/custom-style.php' );
	require_once( INTERFACE_ADMIN_DIR . '/interface-themedefaults-value.php' );
	require_once( INTERFACE_ADMIN_DIR . '/theme-option.php' );
	require_once( INTERFACE_ADMIN_DIR . '/interface-metaboxes.php' );

	/** Load Shortcodes */
	require_once( INTERFACE_SHORTCODES_DIR . '/interface-footer_info.php' );

	/** Load Structure */
	require_once( INTERFACE_STRUCTURE_DIR . '/header-extensions.php' );
	require_once( INTERFACE_STRUCTURE_DIR . '/searchform-extensions.php' );
	require_once( INTERFACE_STRUCTURE_DIR . '/sidebar-extensions.php' );
	require_once( INTERFACE_STRUCTURE_DIR . '/footer-extensions.php' );
	require_once( INTERFACE_STRUCTURE_DIR . '/content-extensions.php' );

	/** Load Widgets and Widgetized Area */
	require_once( INTERFACE_WIDGETS_DIR . '/interface_widgets.php' );
}

?>

My guess is that the directory (INTERFACE_STRUCTURE_DIR . '/header-extensions.php') should be changed, but I’m not sure to what.

Any help is appreciated, thanks.