Hello Doug Beard,
You can get reference to the RadAjaxManager through its static method GetCurrent.
Can you please give us more details on the exact case in which you find difficulties using RadAjaxManager?
To your question, if I have got it right -- yes, you have to add RadAjaxManager before any control tries to use it. I have attached a simple project where similar scenario is demonstrated. Please, feel free to modify it, to better fit your needs.
the Telerik team