由于你没有提供代码示例，我将只使用虚构的值。
假设GridView中有这些控件：

<ComboBox Name="Families" SelectionChanged="Families_SelectionChanged" Grid.Row="1"/>
<ComboBox Name="FamilyTypes" Grid.Row="2"/>

在Families combobox中：

Families.ItemsSource = new List<string> ()
    {
      "Family 1",
      "Family 2",
      "Family 3",
    };

代码是这样的：

private void Families_SelectionChanged ( object sender, System.Windows.Controls.SelectionChangedEventArgs e )
    => FamilyTypes.ItemsSource = Families.SelectedItem switch
    {
      "Family 1" => new List<string> () { "Type 1", "Type 2", "Type 3" },
      "Family 2" => new List<string> () { "Type 3", "Type 4", "Type 5" },
      "Family 3" => new List<string> () { "Type 1", "Type 5" },
      _ => null
    };