Hi,

Are you familiar with wordpress filters?

I've included filter for this in file stachethemes_event_calendar\assets\php\class.mail.php line 102:

        $filter = apply_filters('stec_send_event_changed_mail', array(
            'emails'  => $email_list,
            'subject' => $subject,
            'content' => $content
                ), $old_event, $new_event);

Example:

add_filter('stec_send_event_changed_mail', function($settings, $old_event, $new_event){
    
    // Additional emails list
    $additional_emails = array(
        '[email protected]',
        '[email protected]'
    );
    
    // Merging new email list with the default emails
    $settings['emails'] = array_merge($additional_emails, $settings['emails']);
    
    return $settings;
}, 10, 3);

Okay, let me know if you have any questions.

Note: by default the calendar sends email notifications to the event's attendees and organizers.