I can’t figure out the name of this movie

There was an older boy and older girl and then a little boy with curly hair. They all ran away for some reason. The little boy used to have a sister but she died by drowning I think. The way we found this out was because someone was making fun of the little boy but I don’t know that could be wrong. The older boy and older girl kissed and it might’ve happened in an empty pool but maybe not. I can barely remember this movie it’s been so long sense I’ve watched it and no one ever knows what I’m talking about.