This snippet loads custom templates defined in the $custom_templates array from a /templates/ directory in your plugin. Use this to override templates within EE that don't automatically search for custom templates.

tw_ee_load_custom_templates.php

<?php

// This function allows you to load custom templates into Event Espresso for template that do not normally allow for it.
// If EE uses locate_template to load the template you can load it from your theme's root directory, if not use this.
function tw_ee_load_custom_templates( $template_path ) {

    // Set the custom templates you want to override here.
    $custom_templates = array(
        'question_groups_main_meta_box.template.php',
    );

    // You could do this dynamically and pull all of the `*.template.php` files from the templates directory using glob.
    // $custom_templates = glob($custom_templates_path . '*.template.php');
    // That will return an array of full paths to the files sound, so you then need to loop over for filenames.

    //Grab the template name being pulled.
    $template_name = basename( $template_path );
    // Set the custom template path for this plugin.
    $custom_templates_path = plugin_dir_path(__FILE__) . 'templates/';
    // Check if we have a custom template for the current one.
    if( in_array($template_name, $custom_templates) ) {
        if( is_readable($custom_templates_path . $template_name) ) {
            return $custom_templates_path . $template_name;
        }
    }
    return $template_path;
}
add_filter('FHEE__EEH_Template__display_template__template_path', 'tw_ee_load_custom_templates');