Nested Gridview Control

How do I access a control that is nested within a gridview.  I have a parent gridview and a child. I would like to access a control within the child gridview.  How to I access the control in RowDataBound for the child gridview.

'Design View
<asp:GridView ID="GVGroup" runat="server" Width="90%"
                    AutoGenerateColumns="False"  DataKeyNames="GroupID">
                    <Columns>
                        <asp:TemplateField  Visible="True">
           & ...