Where any persons unknown or any deceased persons or the heirs and devisees of any deceased persons have been properly joined as defendants but have not appeared either personally or by a personal representative, the court shall determine the extent of the interests of such defendants in the property taken or in the remainder if the property taken is part of a larger parcel and the compensation to be awarded for such interests. The court may determine the extent and value of the interests of all such defendants in the aggregate without apportionment between the respective defendants. In any event, in the case of deceased persons, the court shall determine only the

extent and value of the interest of the decedent and shall not determine the extent and value of the separate interests of the heirs and devisees in such decedent’s interest.