(1)  Where there are more owners than one of the freehold of any land, the sum of the land values, capital values and assessed annual values, respectively, of the interests of all the owners is to be not less than the amounts at which the land value, capital value and assessed annual value, respectively, of that land would be determined if the land were held by one owner in fee simple.

(2)  Where there are more owners than one of a leasehold interest in any land, the sum of the capital values of all the owners is not to be less than the amount at which the capital value of the leasehold interest would be determined under section 13 or 14 .