Public Function FormatWithLines(TextPattern As String, LinePattern() As String, _
  params()()() As Object, Optional lineSeparator As String = vbCrLf) As String
    Dim lines As New List(Of String)
    For a As Integer = 0 To LinePattern.Length - 1
      Dim tmpLines As New List(Of String)
      Dim Pattern As String = LinePattern(a)
      For i As Integer = 0 To params(a).Length - 1
        tmpLines.Add(String.Format(Pattern, params(a)(i)))
      Next
      lines.Add(String.Join(lineSeparator, tmpLines))
    Next
    Return String.Format(TextPattern, lines.ToArray())
  End Function

FormatWithLines("Test1 {0} {1}", {"{0}{1}", "{0}-{1}-{2}"}, {New Object()() _
  {New Object() {"t", 1}, New Object() {"t", 2}}, New Object()() {New Object() _
  {1, 2, 3}}}, ",") ' Ergibt: "Test1 t1,t2 1-2-3"

___________________________________________________________________________________________
Jeder, der behauptet das gesamte .NET-Framework zu kennen ist entweder verrückt oder Sheldon Cooper