What is This Movie Title

Hello, I want to ask for a help if anyone could identify the movie I watched a long time ago, wasn't sure but it's probably released around mid 90s or 2000s.

It's about a widow and widower who had teenage daughter respectively and they are finally married. These two girls enroll the same high school together and the only thing I remember was one of the girls seemed rather weird (in one of scene she hide under the car or something when the family is going to be introduced) and afraid of water or something like that. The other girl seemed envious with weird girl since she sort of brilliant and popular at school, but then the weird girl impressed by her step sister bravery to challenge the wave when she did surfing or something like that.

Also, sometimes the narrative switch between these two girls point of view.

Please do tell if anyone know movie with that description. Thanks a lot.