A friend of mine with two children 9 and 5 (one who is medicated
, the other, 5 is not on any medication
She has run into a phase where both girl are incredibly defiant, do not follow any directions, and then laugh when she tries to discipline them.
This is a point where family talk therapy or at least individual talk therapy would really help. Have you tried that?
Talking to a stranger, and have a stranger explain things to him...