tribal_transfer_liege_title_effect

tribal_transfer_liege_title_effect = {
	create_title_and_vassal_change = {
		type = usurped
		save_scope_as = change
		add_claim_on_loss = no
	}
	scope:title_being_fought_over = {
		change_title_holder = {
			holder = scope:challenger
			change = scope:change
		}
	}
	resolve_title_and_vassal_change = scope:change
	if = {
		limit = {
			root = scope:challenger
		}
		scope:liege_to_challenge = {
			add_opinion = {
				target = scope:challenger
				modifier = usurped_title
			}
		}
	}
	else = {
		hidden_effect = {
			scope:liege_to_challenge = {
				add_opinion = {
					target = scope:challenger
					modifier = usurped_title
				}
			}
		}
	}
}

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