I got it working.
In my sign-up user control, I added this code to the Page_Load
I have a JS function in the sign-up user control:
The sign-up user control also has a RadAjaxPanel which I set it's property
ClientEvents-OnResponseEnd="InitiateAjaxRequest"
After doing that, the Login user control was updated as needed.
I am not sure what adding the AjaxManager to itself as an AjaxSetting does but it worked. Can anyone shed some light on this?
Also what is the argument that ajaxManager.ajaxRequest(arg) takes? I am not sure of the significance of it.