Sounds like we've got another "From Justin to Kelly" on our hands!
The problem with that movie is that Kelly and Justin weren't an item and that it was a dorky beach movie like the ones with Annette Funicello. The concept, itself, wasn't bad at all. They could execute it with Carrie and Anthony if they did it right. Make the singing a natural part of the story-- like in "Duets." Make it a romantic comedy. Then you'll have a great movie and lots of cash from the big box office. Then, imagine the money from the movie soundtrack!