NB.SI

Private Sub Worksheet_Change(ByVal Target As Range)
If Intersect(Target, Union([LETTRES], [RECHERCHES]).EntireColumn) Is Nothing Then Exit Sub
Dim i As Variant
i = Application.Match("zzz", [LETTRES].EntireColumn)
If Val(CStr(i)) < [LETTRES].Row Then i = [LETTRES].Row
[LETTRES].Resize(i - [LETTRES].Row + 1).Name = "LETTRES" 'renomme la plage
i = Application.Match("zzz", [RECHERCHES].EntireColumn)
If Val(CStr(i)) < [RECHERCHES].Row Then i = [RECHERCHES].Row
[RECHERCHES].Resize(i - [RECHERCHES].Row + 1).Name = "RECHERCHES" 'renomme la plage
i = [LETTRES].Cells(1) 'mémorise
Application.EnableEvents = False
[LETTRES].Cells(1) = i & " " 'modification de la plage
Set d = Nothing
[LETTRES].Cells(1) = i 'force le recalcul de la fonction
Application.EnableEvents = True
End Sub