I remember this movie, where a family moves to a new place close to the sea or ocean. Only the mother is there, the father died in a plane accident, there is a girl and a boy (maybe a third one too). They discover a monster in the sand, they become friends. They appear to be able to do magic, they can duplicate themselves multiple times to do chores, the girl practises the violin (everybody hates it). Later, the kids grow angel like wings, and they fly somewhere. I also remember as if someone tried to do experiments on the monster, might have seemed to kill it too. But after a good amount of crying he appears to be okay. I’m Hungarian, so this movie’s title is in Hungarian too. We remeber it to be “az”.