dependent combo boxes

I have 3 combo boxes which are dependent to each other. On combo box 3, I want to add another list which it will depend on both combobox1 and 2. I'm using these code.

Private Sub UserForm_Initialize()

With ComboBox1
    .AddItem "Animals"
    .AddItem "Sports"
    .AddItem "Food"
End With

End Sub

Private Sub ComboBox1_Change()

Dim index As Integer
index = ComboBox1.ListIndex

ComboBox2.Clear

Select Case index
    Case Is = 0
        With ComboBox2
            .AddItem "Dog"
            .AddItem "Cat"
            .AddItem "Horse"
        End With
    Case Is = 1
        With ComboBox2
            .AddItem "Tennis"
            .AddItem "Swimming"
            .AddItem "Basketball"
        End With
    Case Is = 2
        With ComboBox2
            .AddItem "Pancakes"
            .AddItem "Pizza"
            .AddItem "Chinese"
        End With
End Select

End Sub

On combo box 3 I want to add another items which it will depend on both combo boxes. Please help. Thanks.