Export Only Child grid to excel from Ajax Update Panel

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ASP.NET4

I have an Ajax update panel, contains Parent grid and child grid. I want to export only child grid on a button click.This is what i have:

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<pre lang="xml"><ajaxToolkit:TabPanel HeaderText="Trigger History" runat="server" Width="100%"><br />
                        <ContentTemplate><br />
                            <asp:GridView ID="gvSurgeDetails" runat="server" AutoGenerateColumns="false"<br />
                                ShowFooter="true" Width="1000px"<br />
                                OnRowDataBound="gvSurgeDetails_OnRowDataBound" OnPageIndexChanging ="gvSurgeDetails_PageIndexChanging" AllowPaging ="true" PageIndex="0" PagerSettings-Mode="Numeric" PagerSettings-PageButtonCount="10" PagerSettings-FirstPageText="First" PagerSettings-LastPageText ="Last"><br />
                                <Columns><br />
                                    <asp:TemplateField ItemStyle-Width="20px"><br />
                                        <ItemTemplate><br />
                                            <a href="JavaScript:divexpandcollapse('div<%# Eval("id") %>');"><br />
                                                <img id='imgdiv<%# Eval("SurgeLevelUpdateID") %>' width="9px" border="0"<br />
                                                    src="Images/plus.gif" alt="" /></a><br />
                                        </ItemTemplate><br />
                                        <ItemStyle Width="20px" VerticalAlign="Middle"></ItemStyle><br />
                                    </asp:TemplateField><br />
                                    <asp:TemplateField HeaderText="Update ID"><br />
                                        <ItemTemplate><br />
                                            <asp:Label ID="lblUpdateID" runat="server" Text='<%#DataBinder.Eval(Container.DataItem,<br />
                                                                    "UpdateID") %>'></asp:Label><br />
                                        </ItemTemplate><br />
                                    </asp:TemplateField><br />
                                    <asp:BoundField DataField="UpdateDate" HeaderText="Updated At" /><br />
                                    <asp:BoundField DataField="By" HeaderText="Updated By" /><br />
                                    <asp:BoundField DataField="Color" HeaderText="Colour" /><br />
                                    <asp:BoundField DataField="Confirmation" HeaderText="CONFIRMATION" /><br />
                                    <asp:TemplateField><br />
                                        <ItemTemplate><br />
                                            <tr><br />
                                                <td colspan="100%"><br />
                                                    <div id='div<%# Eval("UpdateID") %>' style="overflow: auto; display: none; position: relative; left: 15px; overflow: auto"><br />
                                                        <asp:GridView ID="gv_Child" runat="server" Width="98%"<br />
                                                            AutoGenerateColumns="false" ><br />
                                                            <Columns><br />
                                                                <asp:BoundField DataField="Description" HeaderText="Description" /><br />
                                                                <asp:BoundField DataField="Value" HeaderText="Value" /><br />
                                                            </Columns><br />
                                                            <HeaderStyle BackColor="#4D92C1" ForeColor="White" /><br />
                                                        </asp:GridView><br />
                                                        <asp:LinkButton ID="gvChild_Export" OnClick="gvChild_Export_Click" runat="server" Text ="Export" CausesValidation="False" /><br />
<br />
                                                    </div><br />
                                                </td><br />
                                            </tr><br />
                                        </ItemTemplate><br />
                                    </asp:TemplateField><br />
                                </Columns><br />
                                <HeaderStyle BackColor="#0063A6" ForeColor="White" /><br />
<br />
                            </asp:GridView><br />
<br />
                        </ContentTemplate><br />
<br />
                    </ajaxToolkit:TabPanel></pre><br />
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I want to export 'gv_child' on click of 'gvchild_export',If i try to add 'PostBackTrigger', it doesnt recognize the button obviously as its onside the Child Gridview.Is there a way to find button control thats inside the div where child grid is?