Sister and brother playing around lake sister hit head on rock and falls in lake?

I'm not sure what you mean by "old". Two movies with drowned sisters come to mind. Neither one has a body kept in a casket though the first has a shrine at the bottom of the lake.In both of these, the brother blames himself for the accident.

Dementia 13 (1963) It's a b&w film. You can read the plot summary here: en.wikipedia.org/wiki/Dementia_13Haunted (1995) You can read the plot summary here: en.wikipedia.org/wiki/Haunted_(1995_film)I'll look around for other possibilities.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.