Another idea...

As i was writing out the character profiles i thought of another reason why the boy could be following the girl by adding another twist.

We have said that at first we are going to make the boy look as thought he is up to no good by following the girl to the grave yard and make him look a bit eerie on the way the camera angles follow her as thought creeping up on her and looking through the eyes of the boy, then as the film progresses we were going to have the boy in the background of the shots of the girl and have him looking at her, when she drops her pen on the floor he will then go over and help her, this then will make it seem asthough he fancies the girl.

Here's the other twist i thought of, The girl has a photo of her dad with her all the time but it is torn half and it looks asthough someone has been ripped off the other side next to her dad, towards the end of the film i then thought we could end with the twist that the girl is in the grave yard again and she is holding the picture and the boy holds his half of the picture next to hers and the find out that they are brother and sister. almost like the twist in 'Parent trap'.