What do you think of these names?

I personally think that Isabella seems very modern and popular compared to the more old fashioned Roselyn. I would choose to go with Isabelle Serena(I prefer the way this sounds) and Natalia Roselyn(or Rosalie) for the twin sister's name. I believe these match up with eachother the best in terms of style and sound of name. But in the end its totally your choice. Good luck! :)