The ‘appropriate person’ is defined
The reference in IHTA84/S190 (1) to the ‘person liable for
inheritance tax attributable ‘ to the land means the person
who either paid the tax or has an obligation to pay it. If there is
no tax payable on the interest, there is no person liable to pay
the tax. This point was determined in the case of Stoner v IRC
 SPC 288.
In most cases the appropriate person will be the personal representative ( IHTM05012) of the deceased or the trustees ( IHTM16050) of a settlement. For the purposes of this relief both are to be treated as a single and continuing body of persons distinct from the persons who may from time to time act in such capacity, IHTA84/S190 (3).
In practice it may be possible to regard a sale as made by the appropriate person if it is made on their behalf.
X and Y the personal representatives of land specifically devised to Z, who pays the tax, sell the property to A. This might be regarded as a sale by Z.
You should refer any case where it is claimed that land is sold on behalf of the appropriate person to TG.