Developing a simple functionality in a wp website based on woocommerce

Hi, I have a WP website with woocommerce plugin installed both are on latest versions. I have a functionality developed by a developer to pop up an online contract page when customers on check out page and click on place order that they need to click "Approve" on to get the contract sent to the customer with the contact signed in a signature style and with customized contract details. It is all working fine but just one thing i need to develop. I have a check box for terms and conditions and some other required fields in the checkout form that MUST BE filled before the order is completed. When the required fields and the terms and conditions check box are not filled the order is not completed and it turn the error that the required fields and terms and conditions box need to be check before proceeding BUT the email that the developer customized is getting sent anyway which is not what should be the case. What i want is to put if condition or some kind of rule to get the email to be sent ONLY if the required fields are filled and the terms and conditions box is ticked without affecting or changing the code written by the other developer. The required fields in the checkout page are: First Name (Native Woocommerce field) Last Name (Native Woocommerce field) Address (Native Woocommerce field) Town / City (Native Woocommerce field) State / County (Native Woocommerce field) Postcode / Zip (Native Woocommerce field) Email Address (Native Woocommerce field) Phone (Native Woocommerce field) Employment/Assignment Number (A field created by WooCommerce Checkout field editor) The files that the developer worked on to get the email sent wp-content/plugins/woocommerce/includes/[login to view URL] (Core woocommerce file) themes/divi-master/woocommerce/checkout/[login to view URL] (A template override) themes/divi-master/woocommerce/checkout/[login to view URL] (A template override) The developer used Dompdf to create the pdf file that gets send in the contract email. I want this task to be completed in 1 days if possible as i need it urgently.