Identify auto generated TextBox

I want to build a simple properties view where one can change each value.

The properties are grouped by one name like this:

• name1: property1,property2
• name2: property1,property2
• ...

So I created a DataGrid with a template to fill the grid (note that I removed every style property etc. and the text values are also just examples):

<DataGrid>
    <DataGrid.Columns>
        <DataGridTemplateColumn Header="Property Group Name">
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <TextBlock Text="{Binding propertyGroupName}" />
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>
        <DataGridTemplateColumn Header="Property 1">
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <TextBox Text="{Binding property1}" />
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>
        <DataGridTemplateColumn Header="Property 2">
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <TextBox Text="{Binding property2}" TextChanged="TextBox_TextChanged" />
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
        </DataGridTemplateColumn>
    </DataGrid.Columns>
</DataGrid>

As you can see I'm now trying to add a TextChanged event and there is my problem: Where do I get the propertyGroupName information from, since I only need to change the property2 from a specific propertyGroup.

I'm ready for any hint or solution... maybe the 'auto gen datagrid' isn't the best decision here?