Macro to automatically add rows whenever a certain value is entered

Dear experts,
 
I have had some experience with VBscript before but am far from an expert, which is why I would like your help to sort out the following:
 
I am looking for a macro that automaticacly adds 3 rows underneath the cell where the word "cross" is entered. E.g.
 
cell A1     alfa        100
cell A2     beta       200
cell A3     gamma   300
cell A4     Cross     200     -->insert  cell A4    Replace word "Cross" by "Lambda"
                                                        cell A5    delta
                                                        cell A6    epsilon
                                                        cell A7    kappa
Also, all inserted rows need to contain the same formulas as the ones used in cells that are not called "Cross".
 
Hopefully some of you can help.
 
Many thanks in advace for your time and support.
 
KR,
 
H.

Try this:

Option Explicit
Private intPreviousRow As Integer, intPreviousColumn As String
Private strPreviousRow As Integer, strPreviousColumn As String
Private strPreviousCell As String
Private blnChangeFlag As Boolean
Private Sub Worksheet_Change(ByVal Target As Range)
Dim strPreviousCellText As String
 'check to see if the flag has been changed from the ChangeData routine
If blnChangeFlag = True Then
    strPreviousCellText = Range(strPreviousCell).Text
    If UCase(strPreviousCellText) = "CROSS" Then
        ChangeData
    End If
End If
End Sub
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
Dim strRow As String, strColumn As String
Dim intColumn As Integer
intPreviousRow = ActiveCell.Row
blnChangeFlag = True
intColumn = ActiveCell.Column
intPreviousColumn = intColumn + 64
strPreviousColumn = Chr$(Val(intPreviousColumn))
strPreviousCell = strPreviousColumn & LTrim(Str(intPreviousRow))
End Sub
Private Sub ChangeData()
Dim intDeltaRow As Integer, intEpsilonRow As Integer, intKappaRow As Integer
Dim strDeltaCell As String, strEpsilonCell As String, strKappaCell As String
blnChangeFlag = False 'Set to false because Worksheet_Change will be triggered
                        ' when the data is changed below
    intDeltaRow = intPreviousRow + 1
    intEpsilonRow = intPreviousRow + 2
    intKappaRow = intPreviousRow + 3
    strDeltaCell = strPreviousColumn & LTrim(Str(intDeltaRow))
    strEpsilonCell = strPreviousColumn & LTrim(Str(intEpsilonRow))
    strKappaCell = strPreviousColumn & LTrim(Str(intKappaRow))
    Range(strDeltaCell).FormulaR1C1 = "delta"
    Range(strEpsilonCell).FormulaR1C1 = "epsilon"
    Range(strKappaCell).FormulaR1C1 = "kappa"
blnChangeFlag = True
End Sub