Multiple codes in one worksheet_change

Hi,

I am a newbie to VBA and are creating a production sheet. I have two VBA codes which needs to be applied into difference columns. The codes fullfill separate purpose and is working perfectly fine in seperate excel sheets. One code is for automatically dates and the other is for message box pop up.

I need the codes in one sheet. How can I make these codes work in one worksheet_change. Below is my two codes.

Here is the first code and its working perfectly fine if its added alone:

Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Column = 1 Then
Application.EnableEvents = False
Cells(Target.Row, 4).Value = Date + Time
Application.EnableEvents = True
Else
If Target.Column = 12 Then
Application.EnableEvents = False
Cells(Target.Row, 16).Value = Date + Time
Application.EnableEvents = True
Else
If Target.Column = 15 Then
Application.EnableEvents = False
Cells(Target.Row, 16).Value = Date + Time
Application.EnableEvents = True
End If
End If
End If

End sub

MY SECOND CODE:

Private Sub Worksheet_Change(ByVal Target As Range)
Const iDefaultDays As Integer = 84
Dim dtExpected As Date

On Error GoTo Terminate

If Target.Cells.Count > 6 Or Target.Column <> 6 Then GoTo Terminate
If Target.Value = "" Then
Target.Offset(0, 2).ClearContents
GoTo Terminate
End If

Application.EnableEvents = False

If Not IsDate(Target.Value) Then
MsgBox "Invalid value - please enter a date", vbExclamation + vbOKOnly
Target.ClearContents
Target.Select
Else
dtExpected = Target.Value + iDefaultDays
If MsgBox("Expected delivery date: " & dtExpected & String(2, vbCr) & "Accept this date?", vbYesNo + vbQuestion) = vbNo Then
dtExpected = InputBox("Manually enter expected delivery date", , dtExpected)
End If
Target.Offset(0, 2).Value = dtExpected
End If

Terminate:
If Err Then
Debug.Print "Error", Err.Number, Err.Description
Err.Clear
End If
Application.EnableEvents = True
End Sub

Thanks alot!