(1) Where property contracted to be sold for one consideration for the whole of it is conveyed to the purchaser in separate parts or parcels by different instruments, then the consideration shall be apportioned in such manner, as the parties think fit, so that a distinct consideration for each separate part or parcel is set forth in the conveyance relating to such separate part or parcel, and such conveyance shall be charged with ad valorem duty in respect of such distinct consideration.

(2) Where -

(a) any property which consists partly of an interest in residential property is sold to any person and the sale (in this subsection referred to as "the first-mentioned sale") does not form part of a larger transaction or of a series of transactions, or

(b) the sale to any person of property consisting in whole or in part of such an interest forms part of a larger transaction or of a series of transactions,

then the consideration attributable to the first-mentioned sale and the aggregate consideration (other than rent) attributable to that larger transaction or series of transactions, as the case may be, shall be apportioned, on such basis as is just and reasonable, as between that interest in residential property and the other property or part concerned, and that aggregate consideration shall likewise be apportioned as between each other such interest (if any) comprised in that larger transaction or series of transactions and the other property or parts concerned, and notwithstanding the amount or value of the consideration set forth in any instrument -