Actually, the matter of the sudden arrival of the cute little ones was orchestrated by the Book of Destiny.
It had once been a materialized Nen item embodying the Nen ability of Le Eifu's father. After his death, it managed to linger in the world due to certain unknown factors, along with his lingering obsession and emotions.
Although it now belonged to Le Eifu as her own Nen ability, the lingering obsession and emotions belonging to the late father would still pop out from time to time, as if wanting to assert their existence.
Chapter 277