Hi Paul,

you can attach an event to DataFactory.CreatedPage and in that event you check if the page created is of Page Type X, if it is, then create new pages as you please. If you're using EPiServer 6 you can use the code below. Otherwise, just make a HttpModule and do the "same" thing. If you are using PageTypeBuilder you can check if it is the correct page type by "if (e.Page != null && e.Page is PageTypeXClass)"

[EPiServer.Framework.InitializableModule]
    public class PageEventsModule : EPiServer.Framework.IInitializableModule
    {

        private bool _isInitialized = false;
        public void Initialize(EPiServer.Framework.Initialization.InitializationEngine context)
        {
            if (!_isInitialized)
            {
                DataFactory.Instance.CreatedPage += new PageEventHandler(Instance_CreatedPage);
                _isInitialized = true;
            }
        }

        void Instance_CreatedPage(object sender, PageEventArgs e)
        {
            if (e.Page != null && e.Page.PageTypeName == "PageTypeX")
            {
                CreatePageMethod(e.PageLink, "PageTypeA");
                CreatePageMethod(e.PageLink, "PageTypeB");
            }
        }        

        public void Preload(string[] parameters)
        {
            throw new NotImplementedException();
        }

        public void Uninitialize(EPiServer.Framework.Initialization.InitializationEngine context)
        {
            throw new NotImplementedException();
        }
    }