As all the controls are added to the same ajax setting UpdatedControls collection, all of them would be refreshed on every ajax request invoked with the ajaxRequest() method.
To overcome this behavior by adding different ajax settings with different set of updated controls and for initiator control, add a real ajax initiator but the RadAjaxManager. Then you can invoke ajax requests manually with the ajaxRequestWithTarget() method instead.
Please find more information on how to achieve that here
Give it a try and let me know how it goes.
the Telerik team
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