WooCommerce change "Customer Email" to another email that already exist in a custom field after order status changes.

Hi! We are running a woocommerce store which the user enters 2 different emails at checkout. One gets into the WooCommerce Customer Details and the other one shows up in the order in a custom field. When the order change status we need to replace the customer email to the one in the custom field. The system works this way: Employee place and order and enter their boss email, and their own email. The boss gets an email to approve the order, once approved we want the order to update to the customer email which exist in the custom field, so they get the delivery emails etc. We need to work done asap. Thanks!