How we can achieve this? expending childgridview by default once page load over

I am using nestred gridview. showing parent gridview records.. if any of row has records of child gridview. i am showing using expand and collopase button.

this works fine. But this works when you expand on (+ symbol image). it shows child gridview and when collopase(- symbol image), child gridview hides.
aspx.cs
 protected void Page_Load(object sender, EventArgs e)
 {
 if (!Page.IsPostBack)
         {
         using (SqlConnection con = new SqlConnection(sqlconn))
                        {
                            con.Open();
                            string sqlqry = "select figno,name,childflag from parentview";
                            SqlCommand cmd = new SqlCommand(sqlqry,con);
                            SqlDataAdapter adap = new SqlDataAdapter(cmd);
                            DataTable dt = new DataTable();
                            adap.Fill(dt);

                            C1GridView1.DataSource = dt;
                            C1GridView1.DataBind();

                        }
    }

 }
// onrowdatabound action
 protected void childgridbound(object sender, GridViewRowEventArgs e)
 {
     if (e.Row.RowType == DataControlRowType.DataRow)
                {
            Label lblflag = (Label)e.Row.FindControl("lblchild");
            if(lblflag=="Y")
            {
                 using (SqlConnection con = new SqlConnection(sqlconn))
                        {
                            con.Open();
                            string sqlqry = "select id, descript from childgrid";
                            SqlCommand cmd = new SqlCommand(sqlqry,con);
                            SqlDataAdapter adap = new SqlDataAdapter(cmd);
                            DataTable dt = new DataTable();
                            adap.Fill(dt);
                            GridView gvSub = e.Row.FindControl("gvsubstitue") as GridView;
                            gvSub.DataSource = dt;
                            gvSub.DataBind();

                        }

            }
            else{
            }
                 }
 }

aspx:
//javascript:
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
 <script type="text/javascript">

        $("[src*=plus]").live("click", function () {
            $(this).closest("tr").after("<tr><td></td><td colspan = '999'>" + $(this).next().html() + "</td></tr>")
            $(this).attr("src", "../image/Parts/minus.png");
        });

        $("[src*=minus]").live("click", function () {
            $(this).attr("src", "../image/Parts/plus.png");
            $(this).closest("tr").next().remove();
        });
    </script>

    <asp:GridView ID="C1GridView1" Width="1138px" runat="server" ShowFooter="true" OnRowDataBound="childgrid_bound" AutoGenerateColumns="false">
      <Columns>
      <asp:TemplateField HeaderText="FIG#">
           <ItemTemplate>
                   <!-- subgridview for sub items if exists for part-->

                             <img id="imgpartsub" runat="server"   alt = "" style="cursor: pointer" src="../Image/Parts/plus.png" />
                                <asp:Panel ID="pnlOrders" runat="server" Style="display: none">
                                    <asp:GridView ID="gvsubstitue" runat="server" AutoGenerateColumns="false" >
                                        <Columns>
                                       <asp:TemplateField HeaderText="Id">
                                               <ItemTemplate>
                                                    <asp:Label ID="lblidsub" runat="server" Text='<%# Eval("id") %>' Font-Names="Sans-Serif" Font-Size="12px"></asp:Label>
                                               </ItemTemplate><ItemStyle Width="130px" />
                                           </asp:TemplateField>
                                             <asp:TemplateField HeaderText="Descript">
                                               <ItemTemplate>
                                                    <asp:Label ID="lbldessub" runat="server" Text='<%# Eval("descript") %>' Font-Names="Sans-Serif" Font-Size="12px"></asp:Label>
                                               </ItemTemplate><ItemStyle Width="130px" />
                                           </asp:TemplateField>


                                        </Columns>

                                    </asp:GridView>
                                </asp:Panel>

                        <asp:Label ID="lblmfgsub" runat="server" Text='<%# Eval("figno") %>' Font-Names="Sans-Serif" Font-Size="12px"></asp:Label>

                   </ItemTemplate>
                </asp:TemplateField>

         <asp:TemplateField HeaderText="NAME">
         <ItemTemplate>
                <asp:Label ID="lblpartname" Width="278px" runat="server" Font-Size="12px"   Font-Names="Sans-Serif" Text='<%# Eval("name") %>' ></asp:Label>

                        </ItemTemplate>
                       <asp:TemplateField HeaderText="ChildFLAG">
         <ItemTemplate>
                <asp:Label ID="lblchild" Width="278px" runat="server" Font-Size="12px"   Font-Names="Sans-Serif" Text='<%# Eval("childflag") %>' ></asp:Label>

                        </ItemTemplate>

        </asp:TemplateField>



</Columns>

        </asp:GridView>

This works fine when you click on + and - (expand/collapse).

In my case. once page load over, if any parent gridview has child gridview, it should have expaned automatically(- symbol)
Then asusual + and - click (collopse and expand)) should work.

Thank you.