Where the interest of the minor or individual adjudicated incompetent in real estate consists of an estate for life or for years the court or presiding judge may, by order, authorize the guardian to join with the individual holding the reversionary estate in a conveyance of the property to which such interest attaches, so as to fully convey the particular estate, on receiving from the proceeds of the sale a gross sum in satisfaction of such estate or such proceeds or the proper portion thereof to be invested, and the interest thereon paid to the individual having the estate until the termination thereof; in either case the amount to be ascertained as prescribed in s. 786.18. When the proceeds or a proportionate part of such proceeds is received by the guardian for investment, the order of the court or presiding judge must provide for the investment thereof until termination of the particular estate, and then for the payment thereof to the individual entitled thereto.