 <p>We have implemented exactly that kind of feature on the homepage of ilsschools.co.uk using client side onchange event:</p> <pre><code>var com2 = XSP.getElementById("#{id:comboBox2}"); XSP.partialRefreshGet("#{id:comboBox2}", { onComplete : com2.selectedIndex = 0 }); </code></pre> <p>We get the element we want to refresh (i.e. comboBox2 and we do this for comboxBox3, 4 etc as well). Then we use partialRefreshGet to refresh the choices in comboBox2, this can be repeated for 3, 4 and other comboBoxes as well. You can compute the disabled property of a comboBox to disable it. You can compute the selections for a comboBox using SSJS.</p> <p>Hope this helps.</p>