Add Options to Checkboxes (unofficial filter)

This is an unofficial filter, not documented, but works, whereas the documented does not.
Use at your own risk, this is not public…

//filter wpcf_fields_{field-type}_meta_data
//$field_options (options array of field)
//$field (whole field array)
add_filter( 'wpcf_fields_checkboxes_meta_data', 'add_options_to_checkboxes', 10, 2 );

function add_options_to_checkboxes($field_options,$field){
	
	//$options array() 
	//key = option unique ID and 
	//value = arrray() of options settings
	//Of course in real life you generate this, maybe using user data, or post data, whatever you want to add as options to your field
	$options = array(

		//array key used as unique ID of each option
		'option_one' => array( 
			'title' => 'Checkbox 2',//The option title
			'set_value' => '1',//value to save if set
			'display'	=> 'db',//value to display if set
			'display_value_not_selected' =>  '',//value to display if not selected custom
			'display_value_selected' => ''//value to display if selected custom
		),

		'option_two' => array( 
			'title' => 'Checkbox 3',
			'set_value' => '1',
			'display'	=> 'db',
			'display_value_not_selected' =>  '',
			'display_value_selected' => ''
		)

	);

	if ($field['name'] == 'My Checkboxes Field') {//Change to your custom field Name (not slug)
		foreach ($options as $key => $value) {
			$option_slug = 'wpcf-fields-checkboxes-option-' . md5($key);
			if (!in_array($option_slug, $field_options['options'])) {
				$field_options['options'][$option_slug] = $value;	
			}	
		}
	}
	return $field_options;
}

Custom post expiration cron intervals

Sometimes during testing you want the post expiration cron to run at very short intervals, but no short interval is available in the CRED editor. To enable custom cron intervals, add the following code to functions.php:

/* --------------------------------------------- */
// CUSTOM POST EXPIRATION CRON INTERVALS
add_filter ('cred_post_expiration_cron_schedules', 'my_cred_post_exp_cron_func', 10,1);
function my_cred_post_exp_cron_func ($schedules) {
  $schedules['onemin'] = array( 'interval' => MINUTE_IN_SECONDS, 'display' => __( 'Every Minute' ) );
  $schedules['twomin'] = array( 'interval' => 2 * MINUTE_IN_SECONDS, 'display' => __( 'Every 2 Minutes' ) );
  return $schedules;
}

Add or remove custom intervals as needed.