decrease_sibling_causing_trouble_value_effect

decrease_sibling_causing_trouble_value_effect = {
	hidden_effect = {
		if = {
			limit = {
				root = { is_ai = no }
				has_variable = sibling_causing_trouble
				var:sibling_causing_trouble > 1
			}
			change_variable = {
				name = sibling_causing_trouble
				add = -1
			}
		}
		else = {
			remove_variable = sibling_causing_trouble
		}
	}
}

As written in game/common/scripted_effects/00_sibling_effects.txt.