I already thought of that, and the settings you mentioned were already there. For reference, below is the source code. (the code behind only loads data in controls).
Upon selecting an item in cboParent, cboChild is loaded with different sets of items
Selecting a particular item in cboChild populates the five listboxes with items based on cboChild.SelectedValue
After reading your reply, I reviewed the code and the only section that could pose problems is the radajaxmanager -- it's possible that the automatic updates are not defined properly. so I will experiment with it while awaiting for your answer.
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="L.aspx.cs" Inherits="Project1.Folder1.L"
MasterPageFile="~/MasterPage.master" Title="Test ListBox" %>
<%@ Register Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" TagPrefix="telerik" %>
<
asp:Content
ID
=
"Content1"
ContentPlaceHolderID
=
"ContentPlaceHolder1"
runat
=
"Server"
>
<
div
style
=
"width: 100%"
>
<
telerik:RadAjaxManager
ID
=
"RadAjaxManager1"
runat
=
"server"
>
<
AjaxSettings
>
<
telerik:AjaxSetting
AjaxControlID
=
"cboParent"
>
<
UpdatedControls
>
<
telerik:AjaxUpdatedControl
ControlID
=
"cboParent"
/>
<
telerik:AjaxUpdatedControl
ControlID
=
"cboChild"
/>
</
UpdatedControls
>
</
telerik:AjaxSetting
>
<
telerik:AjaxSetting
AjaxControlID
=
"cboChild"
>
<
UpdatedControls
>
<
telerik:AjaxUpdatedControl
ControlID
=
"cboChild"
/>
<
telerik:AjaxUpdatedControl
ControlID
=
"txtIntName"
/>
<
telerik:AjaxUpdatedControl
ControlID
=
"txtPubName"
/>
<
telerik:AjaxUpdatedControl
ControlID
=
"lstDest"
/>
<
telerik:AjaxUpdatedControl
ControlID
=
"lstSource1"
/>
<
telerik:AjaxUpdatedControl
ControlID
=
"lstSource2"
/>
<
telerik:AjaxUpdatedControl
ControlID
=
"lstSource3"
/>
<
telerik:AjaxUpdatedControl
ControlID
=
"lstSource4"
/>
</
UpdatedControls
>
</
telerik:AjaxSetting
>
<
telerik:AjaxSetting
AjaxControlID
=
"lstSource1"
>
<
UpdatedControls
>
<
telerik:AjaxUpdatedControl
ControlID
=
"lstDest"
/>
</
UpdatedControls
>
</
telerik:AjaxSetting
>
<
telerik:AjaxSetting
AjaxControlID
=
"lstSource2"
>
<
UpdatedControls
>
<
telerik:AjaxUpdatedControl
ControlID
=
"lstDest"
/>
</
UpdatedControls
>
</
telerik:AjaxSetting
>
<
telerik:AjaxSetting
AjaxControlID
=
"lstSource3"
>
<
UpdatedControls
>
<
telerik:AjaxUpdatedControl
ControlID
=
"lstDest"
/>
</
UpdatedControls
>
</
telerik:AjaxSetting
>
<
telerik:AjaxSetting
AjaxControlID
=
"lstSource4"
>
<
UpdatedControls
>
<
telerik:AjaxUpdatedControl
ControlID
=
"lstDest"
/>
</
UpdatedControls
>
</
telerik:AjaxSetting
>
</
AjaxSettings
>
</
telerik:RadAjaxManager
>
<
telerik:RadAjaxPanel
ID
=
"RadAjaxPanel1"
runat
=
"server"
>
<%--CssClass="example-panel"--%>
<
table
style
=
"width: 100%; table-layout: fixed;"
>
<%--====================================================================================================--%>
<
tr
>
<%-- Col 1 --%>
<
td
style
=
"vertical-align: middle; height: 2em; width: 6em;"
>
<
asp:Label
ID
=
"Label1"
runat
=
"server"
>Parent</
asp:Label
>
</
td
>
<%-- Col 2 --%>
<
td
style
=
"vertical-align: middle; height: 2em; width: 24em;"
>
<
telerik:RadComboBox
ID
=
"cboParent"
Style
=
"width: 10em;"
runat
=
"server"
AutoPostBack
=
"True"
OnSelectedIndexChanged
=
"cboParent_SelectedIndexChanged"
>
<%--Skin="Office2007"--%>
<
Items
>
<
telerik:RadComboBoxItem
Text
=
"Canada"
Value
=
"CA"
/>
<
telerik:RadComboBoxItem
Text
=
"US"
Value
=
"US"
/>
</
Items
>
</
telerik:RadComboBox
>
</
td
>
<%-- Col 3 --%>
<
td
style="vertical-align: middle; height: 2em; width: 7em; border-style: none; border-width: thin;
border-color: Navy;">
<
asp:Label
ID
=
"Label4"
runat
=
"server"
>Child</
asp:Label
>
</
td
>
<%-- Col 4 --%>
<
td
style="vertical-align: middle; height: 2em; border-style: none; border-width: thin;
border-color: Navy;">
<
telerik:RadComboBox
ID
=
"cboChild"
runat
=
"server"
DataTextField
=
"RT_NameInternal_S"
DataValueField
=
"RT_ChildID_PK"
Style
=
"width: 40.5em;"
AutoPostBack
=
"true"
OnSelectedIndexChanged
=
"cboChild_SelectedIndexChanged"
>
<%--Skin="Office2007" --%>
</
telerik:RadComboBox
>
</
td
>
</
tr
>
<%--====================================================================================================--%>
<
tr
>
<%-- Col 1 --%>
<
td
style
=
"vertical-align: middle; height: 2em;"
>
<
asp:Label
ID
=
"Label3"
runat
=
"server"
>Public Name</
asp:Label
>
</
td
>
<%-- Col 2 --%>
<
td
style="vertical-align: middle; height: 2em; border-style: none; border-width: thin;
border-color: Navy;">
<
telerik:RadTextBox
ID
=
"txtPubName"
runat
=
"server"
Width
=
"19em"
MaxLength
=
"50"
>
</
telerik:RadTextBox
>
</
td
>
<%-- Col 3 --%>
<
td
style
=
"vertical-align: middle; height: 2em;"
>
<
asp:Label
ID
=
"Label2"
runat
=
"server"
>Internal Name</
asp:Label
>
</
td
>
<%-- Col 4 --%>
<
td
style="vertical-align: middle; height: 2em; border-style: none; border-width: thin;
border-color: Navy;">
<
telerik:RadTextBox
ID
=
"txtIntName"
runat
=
"server"
Width
=
"40em"
MaxLength
=
"255"
>
</
telerik:RadTextBox
>
</
td
>
</
tr
>
<%--====================================================================================================--%>
<
tr
>
<
td
colspan
=
"4"
align
=
"center"
>
<
table
>
<
tr
>
<
td
align
=
"left"
>
<
br
/>
Members
</
td
>
</
tr
>
<
tr
>
<
td
>
<%-- Child Members --%>
<
div
style
=
"text-align: left"
>
<
telerik:RadListBox
ID
=
"lstDest"
runat
=
"server"
AllowReorder
=
"true"
AutoPostBackOnReorder
=
"true"
DataKeyField
=
"Inits"
DataTextField
=
"FullName"
EnableDragAndDrop
=
"true"
Height
=
"200px"
SelectionMode
=
"Multiple"
Width
=
"200px"
AllowDelete
=
"true"
ButtonSettings-ShowDelete
=
"true"
>
<
Items
>
</
Items
>
</
telerik:RadListBox
>
</
div
>
</
td
>
</
tr
>
</
table
>
</
td
>
</
tr
>
<
tr
>
<
td
colspan
=
"4"
align
=
"center"
>
<%--====================================================================================================--%>
<
table
>
<
tr
style
=
"text-align: left;"
>
<
td
>
Source #1
</
td
>
<
td
>
Source #2
</
td
>
<
td
>
Source #3
</
td
>
<
td
>
Source #4
</
td
>
</
tr
>
<
tr
>
<
td
align
=
"center"
>
<%-- Source #1 --%>
<
div
style
=
"text-align: left"
>
<
telerik:RadListBox
ID
=
"lstSource1"
runat
=
"server"
AllowReorder
=
"true"
AllowTransfer
=
"true"
AutoPostBackOnReorder
=
"true"
AutoPostBackOnTransfer
=
"true"
DataKeyField
=
"Inits"
DataTextField
=
"FullName"
EnableDragAndDrop
=
"true"
Height
=
"200px"
SelectionMode
=
"Multiple"
TransferToID
=
"lstDest"
Width
=
"200px"
>
<
Items
>
</
Items
>
</
telerik:RadListBox
>
</
div
>
</
td
>
<
td
align
=
"center"
>
<%-- Source #2 --%>
<
div
style
=
"text-align: left"
>
<
telerik:RadListBox
ID
=
"lstSource2"
runat
=
"server"
AllowReorder
=
"true"
AllowTransfer
=
"true"
AutoPostBackOnReorder
=
"true"
AutoPostBackOnTransfer
=
"true"
DataKeyField
=
"Inits"
DataTextField
=
"FullName"
EnableDragAndDrop
=
"true"
Height
=
"200px"
SelectionMode
=
"Multiple"
TransferToID
=
"lstDest"
Width
=
"200px"
>
<
Items
>
</
Items
>
</
telerik:RadListBox
>
</
div
>
</
td
>
<
td
align
=
"center"
>
<%-- Source #3 --%>
<
div
style
=
"text-align: left"
>
<
telerik:RadListBox
ID
=
"lstSource3"
runat
=
"server"
AllowReorder
=
"true"
AllowTransfer
=
"true"
AutoPostBackOnReorder
=
"true"
AutoPostBackOnTransfer
=
"true"
DataKeyField
=
"Inits"
DataTextField
=
"FullName"
EnableDragAndDrop
=
"true"
Height
=
"200px"
SelectionMode
=
"Multiple"
TransferToID
=
"lstDest"
Width
=
"200px"
>
<
Items
>
</
Items
>
</
telerik:RadListBox
>
</
div
>
</
td
>
<
td
align
=
"center"
>
<%-- Source #4 --%>
<
div
style
=
"text-align: left"
>
<
telerik:RadListBox
ID
=
"lstSource4"
runat
=
"server"
AllowReorder
=
"true"
AllowTransfer
=
"true"
AutoPostBackOnReorder
=
"true"
AutoPostBackOnTransfer
=
"true"
DataKeyField
=
"Inits"
DataTextField
=
"FullName"
EnableDragAndDrop
=
"true"
Height
=
"200px"
SelectionMode
=
"Multiple"
TransferToID
=
"lstDest"
Width
=
"200px"
ButtonSettings-Position
=
"Top"
ButtonSettings-TransferButtons
=
"TransferAllFrom,TransferFrom"
CheckBoxes
=
"true"
>
<
Items
>
</
Items
>
</
telerik:RadListBox
>
</
div
>
</
td
>
</
tr
>
</
table
>
</
td
>
</
tr
>
<
tr
>
<
td
align
=
"right"
colspan
=
"4"
style
=
"width: 100%"
>
<
telerik:RadButton
ID
=
"cmdSave"
runat
=
"server"
Text
=
"Save"
>
</
telerik:RadButton
>
<
telerik:RadButton
ID
=
"cmdCancel"
runat
=
"server"
Text
=
"Cancel"
>
</
telerik:RadButton
>
</
td
>
</
tr
>
</
table
>
</
telerik:RadAjaxPanel
>
</
div
>
</
asp:Content
>