You could try this code with a custom function hooked in woocommerce_email_recipient_new_order
filter hook:
add_filter('woocommerce_email_recipient_new_order', 'adding_vendor_email', 10, 2);
function adding_vendor_email( $recipient, $order ) {
if ( ! is_a( $order, 'WC_Order' ) ) return $recipient; // (Optional)
// Your code or conditions to get the vendor email (if needed)
$recipient .= ",vendor@yourdomain.com";
return $recipient;
}
You will need to customize this custom hooked function to get the email dynamically…
Code goes in function.php file of your active child theme (or theme) or also in any plugin file.
This code is tested and works
You could also use woocommerce_email_attachments
filter hook… see this related thread