A few high-level arcane spellcasting monsters, such as the Lich from the Monster Manual, also have lair actions.
Such spellcasters can prepare then cast Shapechange on themselves to become an Ancient Metallic Dragon (such as a Brass one), while keeping some things:
You retain the benefit of any features from your class, race or other source and can use them, provided that your new form is physically capable of doing so.
It is my understanding that the above would allow the Lich to keep its Lair actions in dragon form.
Such dragons have a special Change Shape ability to transform into a humanoid or beast (such as a rabbit) while keeping certain things:
[...] retains its alignment, hit points, Hit Dice, ability to speak, proficiencies, Legendary resistances, lair actions, and Intelligence, Wisdom and Charisma scores, as well as this action.
It is clear from the Monster Manual's errata that the Lich could not gain the Dragon's lair actions (or the resulting beast/humanoid lair actions, if any):
If a creature assumes the form of a legendary creature, such as through a spell, it doesn't gain that form's legendary actions, lair actions, or regional effects.
But what I'm wondering here is whether the now-twice-transformed creature would retain its initial form's lair actions.
In this example, would the Lich-transformed-into-an-Ancient-Brass-Dragon-transformed-into-a-Rabbit keep its Lich lair actions?