In all cases in which any person of unsound mind or any minor shall hold an interest as tenant in common with others in one or more parcels of land or realty in this state, and there shall be no valid authority to sell such interest vested in any person by the terms of any instrument under which such person of unsound mind or such minor holds such interest, and such sale shall not be prohibited or restricted by such instrument, it shall be lawful for the guardian of such minor or person of unsound mind to join the other tenants in common in selling any such parcel of land or realty for a division of proceeds thereof, such sale to be made either publicly or privately, and upon such terms as to payment and security for unpaid installments as such guardian may deem to the interest of his ward, subject, however, to such sale being set aside as provided in this article.