Can you please explain how Grandpa Harvey was able to get dream Jade's corpse to their island home? Or for the man to get into the Medium in the first place? The other guardians were dragged along with the kids, but Grandpa Harley was dead by then. And how did he time travel to the future in order to collect the said corpse and come back again in order for Jade to become familiar with her dead dreamself?
He used the teleporters in the Frog Temple in the past but since the Medium doesn’t exist until the players enter he was teleported into the future where he collected Jade’s dead dreamself and brought it back into the past with him.