Update: we found one of the babies dead this morning. No idea why other than her history, as she had been eating weekly and acting like any other juvenile ball python, no signs of illness, and the last time we brought in a new snake was January, 2023. She was in a rack with 8 other snakes who are fine, and there are 35 other snakes in that room that are fine.
This is why survivors of partho clutches or litters should always be disclosed to buyers, and the babies sent to pet homes rather than breeder homes.