Getting Macro To Work On Several Ranges On Same Sheet

I have the following Macro:

Code:

Private Sub Worksheet_Change(ByVal Target As Range) ' Code goes in the Worksheet specific module
Dim rng As Range
' Set Target Range, i.e. Range("A1, B2, C3"), or Range("A1:B3")
Set rng = Target.Parent.Range("C13:D25")
' Only look at single cell changes
If Target.Count > 1 Then Exit Sub
' Only look at that range
If Intersect(Target, rng) Is Nothing Then Exit Sub

[code]....

Which does not allow entry to range C13:D25 if D12 is empty. Works great!But I need it to work across ranges E13:F25 if F12 is empty, G13:H25 if G12 is empty etc.

I tried copy pasting the same macro over and over again but renaming it to e.g. Worksheet_Change2 causes the Macro to stop working completely.What am I doing wrong?