jQuery(document).ready(function() {
  
  
    jQuery("#register_email").val("xx@xxx.com");
    jQuery(".hkform-group.control-group.hikashop_registration_email_line").hide();
    // Attach a change event handler to the radio buttons
    jQuery("input[name='data[register][registration_method]']").change(function() {
        // Check if the radio button with value 2 is checked
        if (jQuery(this).val() === "2") {
            // If yes, fill in the email
            jQuery("#register_email").val("xx@xxx.com");
            jQuery(".hkform-group.control-group.hikashop_registration_email_line").hide();
        } else {
            // If not, you can optionally clear the email field
            jQuery("#register_email").val("");
			jQuery(".hkform-group.control-group.hikashop_registration_email_line").show();
        }
    });
 
});  
we added these code into checkout / sub_block_login_registration.php
dont think it is related
when every one using guest checkout, they all share the same email, would like to know how the system if it should load the account and address or not