Where the judgment debtor claims or is proved to be rendering services to or employed by a relative or other person, or by a corporation owned or controlled by a relative or other person, without salary or compensation, or at a salary or compensation so inadequate as to satisfy the court that the salary or compensation is merely colorable and designed to defraud or impede the creditors of the debtor, the court may direct the employer-garnishee to make payments on account of the judgment in installments, based upon reasonable value of the services rendered by the judgment debtor under his employment or upon the judgment debtor's then earning ability.