Maybe the easiest way to do this is to place an AJAX Panel (UpdatePanel or RadAjaxPanel) inside the Admin and Content docks and add the controls directly to the AJAX Panel. Another way is to wrap the entire content (the DockZone with the docks) with an AJAX Panel. Please note that in case your docks perform postbacks on movement they must be docked or an error might occur if you drag a dock outside the AJAX Panel.
Since the user controls also contain AJAX panels, you should carefully configure the AJAX triggers so that only the right panels will get updated.
PS: You should take a look at the following projects from our Code Library. They might give you an idea of how to achieve this:
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