If the owner of the property or of any interest therein is unknown or if there is a possibility of unborn remaindermen having an interest, notice shall be served on the person in actual possession of the property or interest and also on the judge of the probate court of the county where the property or interest is located, who shall act for the unknown owner as provided for unrepresented minors in Code Section 22-2-21, provided that, whenever the unknown owner may appear, he may ask for and have another assessment under the terms of this title and he shall receive the amount then assessed. If the second assessment is less than the first, the judge of the probate court shall return the surplus to the person originally condemning.