vc_before_init hook

custom.php

<?php
	add_action('vc_before_init', 'vc_before_init_actions');
	function vc_before_init_actions()
	{
		require_once(get_template_directory() . '/vc_templates/breadcrumb.php');
		require_once(get_template_directory() . '/vc_templates/blockquote.php');
		require_once(get_template_directory() . '/vc_templates/post_grid_filters.php');
	}