Section 3. Upon a petition by an executor or administrator to sell real estate of a deceased person, if it shall appear that a surviving husband is or may be entitled to an estate of curtesy, or a surviving wife to an estate of dower in the premises to be sold, the probate court may, if the petitioner so requests, and after notice, license him to sell the same free and clear of any such interest or claim on the part of the surviving husband or wife. One third of the proceeds of the sale shall thereupon be set apart for the period during which such curtesy or dower may be claimed; and if a claim is duly made therefor, the court shall appoint a trustee to administer the same in accordance with section thirty-five of chapter two hundred and forty-one, unless the parties in interest shall otherwise agree upon a division of the proceeds without the appointment of a trustee, and the probate court may approve any such agreement on the part of the executor or administrator.