Set check on chckbox of a Gridcol when setting ItemSource

Question

I have bounded DataGrid, in which I have CheckBoxColumn as its 1st col and Checkbox in header. If that is checked then the data of that row is retrieved. The code is :

 <DataGrid AutoGenerateColumns="False" Name="dgvSiSelection" BorderBrush="#FFB7B39D" Background="LightYellow" RowBackground="LightGray" AlternatingRowBackground="#FFFFFFF5" BorderThickness="10" FontSize="13" FontFamily="Segoe UI" CanUserAddRows="False">

    <DataGrid.Columns>
          <DataGridCheckBoxColumn Binding="{Binding BoolProperty, Mode=TwoWay}"/>
          <DataGridTextColumn Header="" Binding="{Binding SiHeader}" MinWidth="108" IsReadOnly="True"/>
          <DataGridTextColumn Header="Number of Chemicals" Binding="{Binding S_NumberOfCases}" />
          <DataGridTextColumn Binding="{Binding S_Value1}" >
                <DataGridTextColumn.Header>
                         <Grid>
                              <Grid.ColumnDefinitions>
                                  <ColumnDefinition/>
                                    <ColumnDefinition/>
                              </Grid.ColumnDefinitions>
                              <TextBlock Grid.Column="1" Text="Value1"/>
                              <CheckBox Name="chkNValue1"  Grid.Column="0" Width="16" IsChecked="{Binding RelativeSource={RelativeSource AncestorType={x:Type DataGridColumn}}, Path=DataContext.AllItemsAreChecked}" />
                      </Grid>
        ..................

In above Grid, I have checkbox at the 1st col and on headers too along with title. Based on selection of respective checkbox data is retrieved.

When I set ItemSource of the DaraGrid, the items are displayed properly but the checkbox of 1st col & along with column headers are not selected. I can't find a way to set the checkbox of 1st row.

Also how to make chkNValue1 selected ?

How do I set it or what to do to how to accomplish this.

CODE I import data and load the datagrid accordingly :

        List<SIData> sd = mw.xlsImpExp.GetStep5SiList();

        dgvSiSelection.ItemsSource = sd;

        // SI Grid - Check the ValueX checkbox on header
        for (int i = 0; i < sd.Count; i++)
        {
            SIData s = sd[i];

            if (s.S_Value1 > 0)
                chkNValue1.IsChecked = true;
            if (s.S_Value2 > 0)
                chkNValue2.IsChecked = true;
            if (s.S_Value3 > 0)
                chkNValue3.IsChecked = true;
            if (s.S_Value4 > 0)
                chkNValue4.IsChecked = true;
            if (s.S_Value5 > 0)
                chkNValue5.IsChecked = true;
        }

To check the checkboxes for ValuesX columns, I managed the above code. But wondering if their could be anything more simple and easy than looping.

For col1 checkbox, I have no code at all. I have no clue how do I implement that. I need to set that mainly while setting the ItemSource of the grid.

Any guidelines, help is appreciated.

Thanks