Unfortunately, our WebFlyPostBackManager have not support render control using WebUserControl. However, you could contain the WebUserControl in an ASP Panel and use the Panel object as the RenderControl parameter to refresh all the control in WebUserControl.

Another suggestion, if you do not prefer to pass the WebFlyPostBackManager you could manually select the modified control in the WebUserControl and invoke the RenderControl on the selected modified control. 

Hello Glenn,

          Follow your suggestion, I contain the WebUserControl in an ASP Panel .However,when the panel is dynamically created,it doesn't work too.

In my test a dynamically created panel that I created during PageLoad server side event handler could also be used in order to refresh the display.

However, a dynamically created panel during the execution of WebFlyPostBackMethod will not work. In that case, the parameter for the RenderControl would be the control which you attached the panel to, not the ASP Panel.