Public colMyForms As Collection

Public Function OpenMyForm(lngRecordID As Long)
    Dim frmMyFormCopy As Form_frmMyForm

    If colMyForms Is Nothing Then Set colMyForms = New Collection

    Set frmMyFormCopy = New Form_frmMyForm
    frmMyFormCopy.Filter =  "RecordID = "  & lngRecordID 
    frmMyFormCopy.FilterOn = True
    DoCmd.MoveSize colMyForms.Count *  150  +  3 . 65  *  1440 , colMyForms.Count *  720  +  1080  'величина смещений на ваш вкус
    frmMyFormCopy.Visible = True

    colMyForms.Add frmMyFormCopy, frmMyFormCopy.hWnd & ""

    Set frmMyFormCopy = Nothing 
End Function

Private Sub Form_Close()
On Error Resume Next
colMyForms.Remove Me.hWnd & ""
End Sub