Modifying data validation code

I have this existing code that I'd like to modify for another cell:

Private Sub Worksheet_Change(ByVal Target As Range)

Range("$G$16").Validation.Delete
If Target.Address = "$E$14" Then
    If Target.Value = Range("N6").Value Then
        Range("$G$16").Validation.Delete
    Else
        Range("$G$16").Validation.Add Type:=xlValidateList, AlertStyle:=xlValidAlertStop, Operator:= _
        xlBetween, Formula1:="=$X$13:$DI$13"
    End If
End If
End Sub

I have two questions:

1. If E14=N6 and if F15=N8 then add data validation X13-DI13 to G17. What to modify in the code above?
2. If I want to add this code in the hidden sub worksheet, can I just paste it underneath the existing code (here shown above)?

Thank you for your help!