Schedule change for second semester

I did some major changes to my second semester schedule and I was wondering who I have to contact at U of M to let them know about this. I got deferred early action and I plan on writing a letter of intent about my interest in going there as well as update them on my senior year. Should I just mention my new schedule in that or do I actually have to call their office since it would mean that the common app would need to be updated as we were required to say our senior year schedule on that.
If you were wondering, my second schedule used to be:
1-Spanish III
2-AP Calc BC
3-Biology II
4-AP English
5-Psychology
6-Band

Now it’s:
1-Spanish III
2- AP Calc AB (I struggled in BC)
3-Biology II
4- AP English
5- Organic Chemistry (took instead of psych to still strengthen my schedule since I dropped BC)
6-Band

Thank you!
P.S. Will it reflect badly on me dropping BC into AB? I didn’t want to continue to struggle and I wanted to show the admissions that I’m really dedicated to learning, and still want to challenge myself without failing miserably so that’s why I decided to take AB instead. (It’s not like I dropped BC at the start of the year, I actually spent an entire semester in it and did fairly decent.)
Thank you so much!

You should email the changes to admissions to the main email address. You can include any updates to your ECs, and confirm your continued interest at the same time.

@intparent would it be better to email my regional counselor or just the general admissions?

Well, my experience has been that the web sites aren’t always up to date with who those people are. People wit, change regions, go on sick leave, etc. And colleges are not great about making the updates in a timely manner. That is why I recommend the main address. They will make sure it gets to whoever is responsible for your region.