Linda,
I am glad you still need help, and we are here to provide it!
So the new Fantasyland is not necessarily filled with tons of new attractions, but there is still a lot to do. For both the
Enchanted Tales with Belle and
Under the Sea - Journey of the Little Mermaid you will want to visit each within the first hour to hour and a half that the park is open to keep from having to experience VERY long lines.
You will also want to budget some time to meet Ariel after the second ride, and you will want to walk around and explore the different themed zones of this land, including Gaston's Pub and the courtyard area in front of it. Another area of note is the Rapunzel themed section that has many of the recognizable sun on purple background art throughout. Greetings with characters in both lands are pretty frequently featured in these areas.
I would tell you that you should plan on hitting the new Fantasyland first thing after the park has opened, and expect to stay there through lunch. Lunch at Be Our Guest has been encountering long lines, so while I would prefer a Croque Monsieur from there, I would think of going to Gaston's Pub instead.
So I have said here that basically half a day would/could be spent here. You may also find that a return visit might be warranted, at least by your twins. It is a pretty magical area!
Have a magical vacation!