Sounds like Satan is missing the boat here. Why doesn't he appear more often to more children with similar messages? In fact, if it's this easy for him, seems to me he would be making these kinds of apparitional appearances (using children) all the time. I think you're selling yourself short to think that all apparitions are the work of Satan.
Apparitions are of Satan. I don’t care who they pose as.
Fine. Put your faith in apparitions of indeterminate origin.
See where it gets you, but you can’t say you weren’t warned.