Protected Friend Property _ProgrammDts()
        Get
            Return Me.ProgDts
        End Get
        Set(ByVal value)
            Me.ProgDts = value
        End Set
    End Property

Private Sub UF_Mandant_Load(ByVal sender As Object, ByVal e As _
  System.EventArgs) Handles Me.Load
        Me.MandantBindingSource.DataSource = _ProgrammDts
    End Sub

  Dim frmMandant As New UF_Mandant
                frmMandant._ProgrammDts = _ProgrammDts
                frmMandant.ShowDialog()

Private Sub UF_Projekt_Load(ByVal sender As Object, ByVal e As _
  System.EventArgs) Handles Me.Load
        Me.MandantBindingSource.DataSource = _ProgrammDts
        Me.ProjekteItemsBindingSource.DataSource = _ProgrammDts
        Me.ProjekteBindingSource.DataSource = _ProgrammDts
    End Sub

Danke für die Hilfe

Gruß Christian