Hi,

Add this filter in your theme functions.php file:

add_filter('stec_builder_front_elements', function($elements) {

    $calendar_id = 1; // set to the calendar id number
    
    $elements['calendar'] = array(
        sprintf('<input type="hidden" name="calendar_id" value="%d" />', $calendar_id)
    );
    
    return $elements;
});

Change $calendar_id value to your calendar id.

Try out this filter:

/**
 * Only super user and event authors can edit their events
 */
add_filter('stec_user_can_edit_event', function($default, $event) {
    if (is_super_admin()) {
        return true;
    }
    $current_user_id = get_current_user_id();
    if (is_user_logged_in() && $event->get_author() === $current_user_id) {
        return true;
    } else {
        return false;
    }
    
}, 10, 2);