(legal malpractice case against lawyer who drafted will that contained reference to separate written memorandum in which decedent was to list specific bequests of tangible personal property; attorney gave decedent separate written memorandum form; decedent did not sign the form or have it witnessed and attorney never saw form after giving it to decedent; post-death, decedent's heirs and estate entered into settlement declaring that form was invalid and heirs sued attorney for malpractice; trial court ruled for attorney on basis that he did not owe unknown beneficiaries any duty; appellate court reversed on basis that attorney owed duty to unknown, intended beneficiaries because he provided her with the separate written memorandum and knew decedent intended to benefit third parties by means of the form).