vanlueckn

Hi`Hello,

thank you very much for the answer.

I create the custom field as follows:

add_action( 'cmb2_admin_init', 'cmb2_metaboxes' );
/**
 * Define the metabox and field configurations.
 */
function cmb2_metaboxes() {

	/**
	 * Initiate the metabox
	 */
	$cmb = new_cmb2_box( array(
		'id'           => 'vlck_syncbox',
		'title'        => 'Synchronisation - Einstellungen',
		'object_types' => array( 'post', ), // Post type
		'context'      => 'normal',
		'priority'     => 'high',
		'show_names'   => true,
	) );

	$sites       = [];
	$sitesOption = get_option( 'wp_api_mcs_sites' );
	if ( $sitesOption ) {
		foreach ( $sitesOption as $url => $site ) {
			$sites[ $url ] = $url;
		}
	}

	$fieldId = $cmb->add_field( array(
		'name'    => 'Ziele',
		'desc'    => 'Ziele mit denen dieser Beitrag synchronisiert werden soll.',
		'id'      => 'vlck_field_sync_to',
		'type'    => 'multicheck',
		'options' => $sites,
	) );

	if ( $fieldId ) {
		add_option( 'vlck_sync_field_id', $fieldId );
	}
}

I then need to adjust the available options of the Custom Field in another method from time to time. For example, at the beginning I have only two check boxes in the multi-checkbox field, but later I need three or even four