CONCATENER deux cellules dans autre cellules (VBA)

Option Explicit
Private Sub Worksheet_Change(ByVal Target As Range)
If Not Intersect(Target, Range("A7")) Is Nothing Then
If Target = "" Then Target = "Saisir le N° de BE ICI !!!"
End If
If Not Intersect(Target, Range("I2")) Is Nothing Then
If Target = "" Then Target = "Saisir le chemin du répertoire"
End If

If Intersect(Target, [A7]) Is Nothing Then Exit Sub
Dim num$, source, n&, dest(), i&
Dim somme As Variant 'Dim somme As Long 'Dim somme As Integer
Range("A11:G" & Rows.Count).ClearContents 'RAZ
TextBox1 = ""
If [A7].Text = "Saisir le N° de BE ICI !!!" Then Exit Sub
If Not [A7] Like "*KDT/SCO*" Then _
  [A7] = [A7].Text & " /KDT/SCO/ " & Year(Date): Exit Sub
num = [A7].Text
With Sheets("FSE")
  Set source = .Range("A3:M" & .Cells(.Rows.Count, 10).End(xlUp).Row)
End With
n = Application.CountIf(source.Columns(10), num)
TextBox1 = TextBox1.Text & "Nombre des Factures : " & n
If n = 0 Then Exit Sub
source = source 'matrice, plus rapide
ReDim dest(1 To n, 1 To 7)
n = 0
somme = 0
For i = 1 To UBound(source)
  If source(i, 10) = num Then
    n = n + 1
    dest(n, 1) = source(i, 2)
    dest(n, 2) = source(i, 7)
    dest(n, 3) = source(i, 3)
    dest(n, 4) = source(i, 4)
    dest(n, 5) = source(i, 9)
    dest(n, 6) = source(i, 5)
    somme = somme + dest(n, 6)
    dest(n, 7) = source(i, 13)
  End If
Next
[A11:G11].Resize(n) = dest
Cells(n + 11, 6) = somme
Cells(n + 11, 5) = "Total"
End Sub

For i = 1 To UBound(source)
  If source(i, 10) = num Then
    n = n + 1
    dest(n, 1) = source(i, 2)
    dest(n, 2) = source(i, 7) ‘ mon souci est a ce niveau
    dest(n, 3) = source(i, 3)
    dest(n, 4) = source(i, 4)
    dest(n, 5) = source(i, 9)
    dest(n, 6) = source(i, 5)
    somme = somme + dest(n, 6)
    dest(n, 7) = source(i, 13)
  End If