Section 29. If, on such petition, the court or jury find any of the parties entitled to damages, there shall first be found and set forth the total amount of damages sustained by the owners of such property, estimating the same as an entire estate and as if it were the sole property of one owner in fee simple; and such damages shall then be apportioned among the several parties who are found to be entitled thereto, in proportion to their several interests and to the damages sustained by them, respectively, and such apportionment shall be set forth in the finding or verdict; and if it is found that any party has not sustained damage, it shall be set forth in the finding or verdict that he is awarded no damages. The finding or verdict shall be conclusive upon all parties interested who have become parties to the petition.