Customize the email recipient

woocommerce-custom-email-recipient.php

//WooCommerce Email Customizations
add_filter( 'woocommerce_email_recipient_customer_note', array( $this, 'fka_parent_email_recipient_filter_function' ), 10, 2);
add_filter( 'woocommerce_email_recipient_customer_completed_order', array( $this, 'fka_parent_email_recipient_filter_function' ), 10, 2);
add_filter( 'woocommerce_email_recipient_customer_invoice', array( $this, 'fka_parent_email_recipient_filter_function' ), 10, 2);
add_filter( 'woocommerce_email_recipient_customer_processing_order', array( $this, 'fka_parent_email_recipient_filter_function' ), 10, 2);

/**
 * $recipient could be comma separated to send to additional people
 * EX. $recipient .= ', $additonal_recipient'; 
 */
 
function fka_parent_email_recipient_filter_function($recipient, $order) {
  $parent_email_recipient = get_post_meta( $order->id, 'Parent Email', true );
  $recipient = $parent_email_recipient;

  return $recipient;
}