Sub es()
Dim a As Variant, r As Long, Ws As Worksheet
For Each Ws In Sheets(Array("tante", "oncle", "cousin", "cousine"))
With Ws
Set a = .[a1:a1000].Find(What:=Sheets("formulaire").[c13], LookIn:=xlValues, LookAt:=xlWhole)
If Not a Is Nothing Then MsgBox " ce prenom deja present sur feuil...." & Ws.Name: Exit Sub
End With
Next Ws
With Sheets(Range("b3").Text)
r = .Cells(65536, 1).End(xlUp).Row + 1
.Cells(r, 1) = Cells(16, "H")
.Cells(r, 2) = Cells(16, "I")
.Cells(r, 3) = Cells(16, "J")
End With
End Sub