=SI(L2="";W2;W2&REPT(REPT("+";ESTTEXTE(W2))&L2;ESTTEXTE(L2)))
Option Explicit
Function ConcSsDblPlus(ByVal R) As String
Dim TJn() As String, V, X As Integer, P As Integer
ReDim TJn(1 To R.Count)
On Error Resume Next
For Each V In R
Err.Clear: X = WorksheetFunction.Match(V, TJn, 0)
If Err And V <> "" Then P = P + 1: TJn(P) = V
Next V
ReDim Preserve TJn(1 To P)
ConcSsDblPlus = Join(TJn, "+")
End Function
=ConcSsDblPlus($B2:$I2)
=V2&REPT("+";ESTTEXTE(V2)*(V2<>"")*ESTTEXTE(K2)*(K2<>""))&REPT(K2;ESTTEXTE(K2))