InfoPath Dev

Hi, I'm using the following code to add a row to a repeating table. This works fine, however, i want to add the new row on top stead of bottom. How can i archieve this?

            string myNamespace = NamespaceManager.LookupNamespace("my");
            using (XmlWriter writer = MainDataSource.CreateNavigator().SelectSingleNode(
            "/my:myFields/my:group1", NamespaceManager).AppendChild())
            {
                writer.WriteStartElement("group2", myNamespace);
                writer.WriteElementString("field1", myNamespace, "Cell 1");
                writer.WriteElementString("field2", myNamespace, "Cell 2");
                writer.WriteElementString("field3", myNamespace, "Cell 3");
                writer.WriteEndElement();
                writer.Close();
            }

Thanks, Paul