do not reinforce their hallucinations.. just present the reality to them in a calm way.. you should be very observant and always think of his/her own safety and as well as yours.. you'll never know what might happen.. and also by being just there for them like just listening to their problems or what they are thinking really helps them to vent out their feelings... just find some divertional activities like reading books, color, & etc.. where they can express themselves and might help divert their attention when having such hallucinations...