If the estate you are concerned with has an interest in an
unadministered residuary estate (
IHTM22022) that includes an interest in
land, then under IHTA84/S91 your estate may also be treated as
including that interest in land (or part of it) for the purposes of
this relief.
When considering non-qualifying sales (
IHTM33081) under IHTA84/S191 (3) if the
property concerned is comprised in an unadministered estate a
person is treated as having the same interest in the property as
they would have if the administration of the estate had been
completed.