If this patient should be under an existing account (for example, a new child for an existing family account), be sure the Create New Patient checkbox is selected, then click Add to Existing Account. A new search window will appear, displaying any patients with similar names (this list will include deleted and archived patients). Select the account you wish to add the patient to, then click OK.
To make changes to the patient's information, simply open the appointment and click the Advanced View disclosure triangle in the lower left corner of the Appointment Detail window to access all the information available for the patient through the Patients Ability, including Primary, Secondary, Account and Patient tabs. Simply enter whatever information you wish to add, and click Save when you are finished.