Whether patients are part of your database or not they can be added as a Next of Kin.
To view/enter Next of Kin information open up the patients file and go into the Medical Tab.
To specify a non-patient as Next Of Kin
In the Medical tab, click the Non-patient radio button and then type details in the text box that displays:
To specify a patient as Next Of Kin
Click the Patient radio button and then click in the text box to display the selection controls:
Use the (up/down) buttons or
use the (List) button to display the View patients window, from where to select the patient's name: