<p>I agree with @bschoolwiz, no chemistry since 8th grade is a bit of a red flag for a future engineer, but since she’s only a year in to high school, you can see how she handles her schedule sophomore and junior year before you decide about AP chemistry. As far as class rank is concerned, it’s up to her to get As in whatever classes she takes. She appears to have enough weighted classes in her schedule to hit your target GPA, and adding more might backfire. One B erases the weighting bonus of the AP class, but she gets to keep the “rigorous” label for the purposes of college admissions, and she gets to keep the education she receives. Marching band is time consuming, but worth very minute in my opinion. I had a ton of fun, and met my husband in high school marching band. 
The other question to consider would be, if she did not take some or all of the engineering classes because they are unweighted, what would she take instead, and what would she gain, besides a potential bump in class rank, by making the change?</p>