I am trying to add another text box with Purchase Order number where the "add comments about your order" which will then show on the Invoice/Order too when the customer has placed an order. Can you please advise me how to do this.
Thank you for submitting the question here. EShop supports to add custom fields for as address field and they will be appeared at Step 2 and Step 3 of checkout. However, it does not support to add custom field to other steps as Step 4 and Step 5 of checkout.
If you want that, then it requires to customize to EShop. Please contact with me via ticket system so I can help you.