'Why didn't Fuyuki give the trigger to his children long before it was given to me? I don't know if this is luck or a deliberate plan?' thought Ayami strangely.
The reason Fuyuki didn't give it to them back then, he was cultivating some artificial body that he took from his soul. Trigger was like a second life for him and by developing that artificial body, he thought he could have a spare body whenever he couldn't solve the world's problems. Rakugaki had already collapsed and all that remained was that single world. The alternative world should remain intact even though there are only creatures that survive in the void.
The only body that was successfully cultivated was Mafu at that time. He also cultivated his brother's soul which was almost at its limit. Ashina has agreed to this and intends to help her sister bring about peace.