The Event macro asks you to confirm the row you use for z.1 etc.
Private Sub Worksheet_change(ByVal Target As Range)
    'adjust to suit
    If Target.Row <> 1 Then Exit Sub
The alternative AddPics code will search the sheet for z.1 etc. and insert the pictures at these positions.
For i = 1 To 9
        Set c = ws.Cells.Find("z." & i, lookat:=xlWhole)
        If Not c Is Nothing Then
            Sheets("Pics").Shapes("Picture " & i).Copy
            c.PasteSpecial xlPasteAll
        End If
    Next i