Well, I'm still wondering what would happen if the existence of someone's parents were eaten, will the child disappear or what?
That would depend on whether or not the child was born or not. If the child was still in its mother's womb, then its existence would probably be erased because the dependency on its mother's existence is too strong. However, if the child has left the mother's womb, its existence should be defined on its own. It can physically exist without any direct dependencies. In other words, it does not need mother like light needs darkness for definition. Rather, it could arguably live on its own, ignoring the fact that it would most likely die without its parents or guardians. To make a distinction for any age other than that of infancy would reach an absurdity that could erase all of humanity from existence. To say the least, if I had a parent who disappeared because their existence was erased even though I am a college student, then it would not make sense that my existence would be erased, too. I am already living on my own without parental aid. The fact that they gave birth to me has already been completed and accepted into reality for years. For my existence to be erased would imply that I was either killed, died of natural causes, or that I was never born. Of these choices, only two of them depend on life after the womb. The last one depends on life in the womb. Therefore, it is only then that my existence could be erased.