Motion for Leave To Amend or Augment Expert Witness Designation [Memorandum of Points & Authorities] with supporting authorities for the arguments including inter alia a reasonable failure to disclose, or the unexpected unavailability of the, expert; the statutory requirements of surprise, mistake or excusable neglect; the circumstances mandate relief; moving party did not improperly rely on a reservation of rights; his conduct was not willful concealment; the opposing party will not be prejudiced; public policy favors relief; the court has discretion to grant relief consistent with the showing; the trial court ruling presumed correct. 31 pages.