And it would have been a good opportunity to throw in some further hints to read back over after the reveal, if the sisters had been a bit off with Cadence and thrown off weirdly bitter vibes at her "convenient" memory loss, instead they all just seemed to be presented as one big happy family for that summer... They were presented as being so self-serving and ruthless over their competition for the estate though, and their threats to their children for not playing along, that it just didn't seem at all plausible for the three sisters (as well as the grandfather) to apparently all accept that it was solely the adults fault that their children came up with a plan to burn down the house and only one came out alive.