WPF DataGrid合併單元格

<Window x:Class="WpfMergeCells.MainWindow"

<span style="font-size:14px;">        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="625">
    <Window.Resources>
        <DataTemplate x:Key="multipleTable_Header">
            <StackPanel HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
                <Border>
                    <Label Content="郵箱" Width="300" HorizontalContentAlignment="Center"/>
                </Border>
                <Border>
                    <GridSplitter BorderBrush="Black" BorderThickness="0.5" HorizontalAlignment="Stretch"/>
                </Border>
                <Border>
                    <StackPanel Width="300" Orientation="Horizontal">
                        <Label Content="郵箱1" Width="150" HorizontalContentAlignment="Center" VerticalContentAlignment="Center"/>
                        <GridSplitter BorderBrush="Black" BorderThickness="0.5"/>
                        <Label Content="郵箱2" Width="150" HorizontalContentAlignment="Center" VerticalContentAlignment="Center"/>
                    </StackPanel>
                </Border>
            </StackPanel>
        </DataTemplate>

        <DataTemplate x:Key="multipleTable_Clomns" >
            <StackPanel Width="Auto" Height="Auto" Orientation="Horizontal">
                <Border>
                    <TextBlock Margin="1,0,1,0"  Width="150" Text="{Binding 郵箱1}"  HorizontalAlignment="Center"  VerticalAlignment="Center"/>
                </Border>
                <Border>
                    <GridSplitter Background="Black" BorderThickness="0.5" BorderBrush="Black" Margin="0,-1"/>
                </Border>
                <Border>
                    <TextBlock Margin="1,0,1,0"  Width="150" Text="{Binding 郵箱2}" HorizontalAlignment="Center" VerticalAlignment="Center"/>
                </Border>
            </StackPanel>
        </DataTemplate>
    </Window.Resources>
    
    <Grid>
        <DataGrid AutoGenerateColumns="False" Height="260" HorizontalAlignment="Stretch" Margin="12,10" Name="dataGrid1" VerticalAlignment="Stretch" Width="540" ItemsSource="{Binding Collection}">
            <DataGrid.Columns>
                <DataGridTextColumn Binding="{Binding 序號}" Header="序號"/>
                <DataGridTextColumn Binding="{Binding 姓名}" Header="姓名"/>
                <DataGridTextColumn Binding="{Binding 性別}" Header="性別"/>
                <DataGridTextColumn Binding="{Binding 電話}" Header="電話"/>
                <DataGridTemplateColumn HeaderTemplate="{StaticResource multipleTable_Header}" CellTemplate="{StaticResource multipleTable_Clomns}">                    
                </DataGridTemplateColumn>
            </DataGrid.Columns>
        </DataGrid>
    </Grid>
</Window>
</span>