Решил вот так
$arFields = array(
"ORDER_ID" => $ORDER_ID,
"ORDER_PROPS_ID" => 2,
"NAME" => "Юр.лицо",
"CODE" => "UR",
"VALUE" => $_POST['ur']
);
CSaleOrderPropsValue::Add($arFields);
$arFields = array(
"ORDER_ID" => $ORDER_ID,
"ORDER_PROPS_ID" => 2,
"NAME" => "Юр.лицо",
"CODE" => "UR",
"VALUE" => $_POST['ur']
);
CSaleOrderPropsValue::Add($arFields);