No really, you have to punish that dog.
When he poops in your mother's garden, slap him and yell at him.
When he messes with your other dog, slap him and yell at him, and keep saying "bad boy, bad!"
If he keeps doing it, bring the dog to obedience school.
Zeallot, it's like saying "If you hit your son without fatally hurting them, that's child abuse. We have to let them be bad and no physical contact what so ever. Your son is a brat and doesn't listen to you? Don't hit him!"