My son is 7 years old. Sometime I will call him "細佬" as he got an elder sister. Hw, when I talk with him for some topics, I will call his last two name (中文). When we are in public place, I will usually call his last two chinese name. As I think, for 7 years old boy, he got his own thinking, it is one of ways to show that I respect his idea. Now a baby now.
But for elder sister, I will call her 乖女, or double call her last Chinese name. :-P :-P