On single click effect both girdview i want only one gridview

               <asp:SqlDataSource ID="SqlDataSource1" runat="server"
                   ConnectionString="<%$ ConnectionStrings:JAPITConnectionString %>"
                   SelectCommand="SELECT * FROM [viewyn]">



               <asp:GridView ID="ParentGridView" runat="server"
               AutoGenerateColumns="False"
               DataSourceID="SqlDataSource1" DataKeyNames="l_no"

                   onrowediting="ParentGridView_OnRowEditing"
                   onselectedindexchanged="ParentGridView_SelectedIndexChanged">
 <columns>
    <asp:TemplateField HeaderText="Letter Number">
       <itemtemplate>
          <asp:Label id="l_no" Runat="Server"
          Text='<%# Eval("l_no") %>'/>
                   </itemtemplate>


    <asp:TemplateField HeaderText="name Department">
       <itemtemplate>
          <asp:Label id="nam_dep" Runat="Server"
          Text='<%# Eval("nam_dep") %>'/>
                   </itemtemplate>


   <asp:TemplateField HeaderText="number  DEO">
       <itemtemplate>
           <asp:Label id="no_deo" Runat="Server"
           Text='<%# Eval("no_deo") %>'/>
                   </itemtemplate>

               <asp:TemplateField HeaderText="number month">
       <itemtemplate>
           <asp:Label id="no_mon" Runat="Server"
           Text='<%# Eval("no_mon") %>'/>
                   </itemtemplate>


               <asp:TemplateField HeaderText="Letter y/n">
       <itemtemplate>
           <asp:Label id="le_yn" Runat="Server"
           Text='<%# Eval("le_yn") %>'/>
                   </itemtemplate>


               <asp:TemplateField HeaderText="Draft y/n">
       <itemtemplate>
           <asp:Label id="dd_yn" Runat="Server"
           Text='<%# Eval("dd_yn") %>'/>
                   </itemtemplate>







   <asp:TemplateField HeaderText="View">
       <itemtemplate>
           <asp:Button ID="ViewChild_Button"
                 runat="server" Text="+"   CommandName="Edit" />
                   </itemtemplate>
      <edititemtemplate>
           <asp:Button ID="CancelChild_Button"
                 runat="server" Text="-" CommandName="Cancel" />
                           <asp:GridView ID="GrandChildGridView" runat="server"
     AllowPaging="true" PageSize="4"
     DataSourceID="SqlDataSource2">

                   </edititemtemplate>



  <asp:TemplateField HeaderText="View2">
       <itemtemplate>
           <asp:Button ID="ViewChild_Button1"
                 runat="server" Text="+"   CommandName="Edit" />
                   </itemtemplate>
      <edititemtemplate>
           <asp:Button ID="CancelChild_Button1"
                 runat="server" Text="-" CommandName="Cancel" />
                  <asp:GridView ID="GrandChildGridView1" runat="server"
     AllowPaging="true" PageSize="4"
     DataSourceID="SqlDataSource3">


                   </edititemtemplate>




</columns>




               <asp:SqlDataSource ID="SqlDataSource3" runat="server"
                   ConnectionString="<%$ ConnectionStrings:JAPITConnectionString %>"
                   SelectCommand="SELECT * FROM [entry_dd] WHERE ([l_no] = @l_no)">
                   <SelectParameters>
                       <asp:SessionParameter Name="l_no" SessionField="l_no" Type="String" />
                   </SelectParameters>




               <br />
               <asp:SqlDataSource ID="SqlDataSource2" runat="server"
                   ConnectionString="<%$ ConnectionStrings:JAPITConnectionString %>"
                   SelectCommand="SELECT * FROM [Letter_dept] WHERE ([l_no] = @l_no)">
                   <SelectParameters>
                       <asp:SessionParameter Name="l_no" SessionField="l_no" Type="String" />
                   </SelectParameters>

protected void ParentGridView_OnRowEditing(object sender,GridViewEditEventArgs e)
    {

      
        int parent_index = e.NewEditIndex;

        //to set the edit index of the Parent 
        //grid with that of the current row
        ParentGridView.EditIndex = parent_index;
        ParentGridView.DataBind();
        //find the pubid_lbl containing pub_id in that 
        //particular row by using findcontrol method
        GridViewRow row = ParentGridView.Rows[parent_index];
        Label l_nu = (Label)row.FindControl("l_no");

        //save pub_id and edit_index in session for childgridview's use
        Session["l_no"] = l_nu.Text;
        Session["ParentGridViewIndex"] = parent_index;
        
    }