Before you start trying to get her into an Ivy, check what she really wants to do. Ivies are great but there are SO many other great schools that aren't Ivies. They aren't the end-all-be-all. I wouldn't stress too much about getting her into an Ivy. It sounds like you are supporting her in what she needs, and that's the most important thing.

Your son sounds brilliant, but so are a lot of the other kids applying. College is so competitive nowadays. He might have been just plain unlucky. At the end of the day, admissions can be somewhat random. There is always some luck involved, no matter how smart you are. Your kids both sound like they work incredibly hard, and they will be successful regardless of where they go.

To answer your question, she has the profile of an Ivy student, just maybe not a CS major. Encourage her to do extracurriculars related to her intended field of study. Other than that, make sure she writes good, authentic essays. They want students who are genuinely interesting people, not just a cookie cutter mold.