Clicked value on listbox depending on the other listbox

I have an userform in excel that has two listboxes. The first one called 'lstRegion' displays the list of 3 regions (Region AA, BENELUX, Region C) which group different countries. The second list box called 'lstCountry' displays some countries which can be part of one of the region in 'lstRegion'. The user can select/deselect multiple records in 'lstRegion' and automatically, by the Change event, the countries belonging to the selected country will get selected/deselected. The above features works by the below code:

Private Sub lstRegion_Change()
    Dim i As Long
    lstRegionChangedList = True
    lstCountryChangedList = False
    SelectedItemsCountRegion = 0
    
    If lstCountryChangedList = False Then
        SelectDeselectCountryFromRegion lstRegion, lstCountry
        lstRegionChangedList = False
    End If
    
    For i = 0 To lstRegion.ListCount - 1
        If lstRegion.Selected(i) = True Then
            SelectedItemsCountRegion = SelectedItemsCountRegion + 1
'            If SelectedItemsCountRegion > 0 Then
'                Exit For
'            End If
        End If
    Next i
    
    If SelectedItemsCountRegion = 0 Then
        chkRegion_Select_Deselect_All.Caption = "SELECT ALL"
        chkRegion_Select_Deselect_All.Value = False
    ElseIf SelectedItemsCountRegion = lstRegion.ListCount Then
        chkRegion_Select_Deselect_All.Value = True
    End If
    
    If SelectedItemsCountRegion > 0 And SelectedItemsCountCountry > 0 Then
        cmdFind.Enabled = True
    Else
        cmdFind.Enabled = False
    End If
    
End Sub

Private Sub chkCountry_Select_Deselect_All_Click()
    chkCountry_Select_Deselect_All.Caption = IIf(chkCountry_Select_Deselect_All.Value = True, "DESELECT ALL", "SELECT ALL")
    cmdFind.Enabled = chkCountry_Select_Deselect_All.Value
    SelectDeselectAllItemsListBox lstCountry, chkCountry_Select_Deselect_All.Value
End Sub

Now, what I would like to do, Is also the way around: user can also select/deselect one or more countries and automatically the related region will get selected/deselected