Well, Fellini... there is always Fellini.
You must find the note, the correct key, for your story. If you find it, everything will work. If you do not, everything will stick out like elbows.
When you are working on a script, the story itself is not difficult. You say this would happen and then this, resulting perhaps in this. And the dialogue you make as true as you can.
I didn't feel like going any further in this scene with the boy. He was not a professional actor, and if I had pushed the scene any further it would have destroyed the tone of the movie.