Public Class Form1
 
    ReadOnly MAX As Integer = 100
 
    Public Sub Test() Handles MyBase.Shown
 
        Dim Rand As New Random
 
        Dim result1 As Integer() = {1, 100, 2, 3, 4}
        Dim result2 As Integer() = {5, 500, 6, 6, 4}
        Dim result3 As Integer() = {7, 8, 9, 10, 99}
 
        ' Concateno, y...
        ' Elimino duplicados, y...
        ' Selecciono los números inferiores a MAX, y...
        ' Convierto los números mayores a MAX a números aleatorios entre 0 y MAX.
        Dim Result As IEnumerable(Of Integer) =
            (result1.Concat(result2).Concat(result3)).
            Distinct.
            Select(Function(Value As Integer)
                       Return If(Value < MAX, Value, Rand.Next(0, MAX))
                   End Function)
 
        ' Result = 1, RANDOM, 2, 3, 4, 5, RANDOM, 6, 7, 8, 9, 10, 99
        ListBox1.Items.AddRange(Result.Cast(Of Object).ToArray)
 
    End Sub
 
End Class

Public Class Form1
 
    Dim Source As Integer() = {1, 2, 3}
 
    Private Sub Form1_Load() Handles MyBase.Shown
 
        Dim LB As New ListBox
        Me.Controls.Add(LB)
 
        LB.DataSource = Source
        Threading.Thread.Sleep(2000) : Application.DoEvents()
 
        Source = {1, 2, 3, 4, 5, 6}
        LB.DataSource = Source
        Threading.Thread.Sleep(2000) : Application.DoEvents()
 
        LB.DataSource = Nothing
        LB.Items.Add(99)
        Threading.Thread.Sleep(2000) : Application.DoEvents()
 
    End Sub
 
End Class