Right I am gona make a real fool of myself now but hey here goes,
Would I be on the right track thinking it could be somthing to do with the fact that Meg has learnt that she wins everytime ie she frightens the postie off every time. She copes with her coming down by ripping up the post which she has learnt works?
Dunno really, could it be that Meg has to learn that she will not always win? or somat like that anyway ?