Set RadGrid cell value based on RadDropDownList's selected value in another cell, in BatchEdit mode

[Josif]

RadGrid running in batch edit mode. When selecting a value in dropdown "ddlPayrollId", I need to set  "StaffName" to a certain value, let's say 'Joe' . Can you please provide a VB example on how to do it!

ASPX: 
<telerik:GridTemplateColumn UniqueName="PayrollId" DataField="PayrollId">
                        <ItemTemplate>
                            <%# Eval("PayrollId")%>
                        </ItemTemplate>
                        <EditItemTemplate>
                            <telerik:RadDropDownList runat="server" ID="ddlPayrollId" DataValueField="PayrollId" DataTextField="PayrollId" DataSourceID="SqlDataSource1">
                            </telerik:RadDropDownList>
                        </EditItemTemplate>
                    </telerik:GridTemplateColumn>

<telerik:GridBoundColumn DataField="StaffName" UniqueName="StaffName" ReadOnly="True"></telerik:GridBoundColumn>