Please check the requirements for music therapy degrees. IIRC, there are both science and math courses (likely statistics).
This site gives a ton of info about this:
https://www.musictherapy.org/careers/employment/
And for this student, you really must check the disabilities office to see how they handle accommodations…and be sure you have all of the appropriate documentation to get these.
UDayton for musical therapy and the Biomedical Science program at Ohio State or the BS/MD at Cincinnati would be an awesome outcome for both if they could swing it.
This is an interesting thread. OP, I think you will have a lot of people rooting for your kids and hope you continue to share their journey. 
I don’t think it is too early to start identifying schools for application due to your parameters. I also love that your kids want to be near each other. My brother and I (“Irish twins”) attended the same large college and had overlap in our social circles… but enough separation to follow our individual paths too.
You have a lot of good suggestions already. I’ll start brainstorming. I found this website as a starting point for identifying music therapy majors. Obviously any information found should be verified on the school’s websites, but this may help other posters on this thread. Best of luck!
Thank you! I think we’re too early to start making any decisions, but I hope to take a few college tours this summer so they can start thinking about what they’d like.
Your link is for theory not therapy.
Oh good gracious. Now I’m the one who needs my readers! I corrected my post to the site I meant to copy. (and put on my readers 
)
Thanks, that’s the link I’ve been working from.
I just checked the list of schools with music therapy programs and noticed that a lot of them are what I would consider “suitcase” schools. I would say the small list is probably even smaller than it seems unless your son is okay with a campus that clears out on weekends. Then, look at the schools that offer academic support and the list shrinks a bit. I do, however, think that the state flagships on the list are a great place to start for both kids. I believe all of those listed have a good honors program and they are all schools that have a lot to offer. Have your daughter go along on those visits and she might just fall in love as well. As DS said, “There’s nothing you CAN’T do here. You can make a big school seem smaller, but you can’t make a small school bigger”.
DS23 is similar to both of your kids. Grades and recommendations similar to your daughter’s (although applying test optional), but LDs and intense (though different) interests with lots of experience similar to your son’s. I think you are going to find your son a bit more “marketable” than what his grades indicate at schools that look at applicants holistically. They love kids that are committed to something and as long as he can convey that in his essays he will shine.
My kids went to different high schools as well which was great at the time. Now DD really wishes they were back together in college but she isn’t willing to leave the state and DS isn’t willing to stay here. She keeps coming up with schemes to get him to look closer to home. I definitely think they could attend the same school and have separate lives as they already have very strong individual identities. In fact, my guess is they’d rarely do things together. I think it’s more about being on the same break schedule than anything else as they had different schedules in high school which was hard on them and their chosen schools seem to have little overlap. They need that down time together to reconnect.
How important is merit? Saint Joe’s gave my daughter great merit, Villanova zero. The more selective the university, usually the less merit. My twins applied and were accepted to some of the same colleges, she just got more $ than her brother (after being home together during Covid she couldn’t wait to get away and is a 12 hour drive from home.
The Berklee College of Music in Boston comes to mind as one option for your son. I do know of students with less than stellar GPAs who were accepted to Berklee with very strong music abilities, and who then did well there. This of course makes pretty much all of Boston and Cambridge, or even suburbs, as options for your daughter. There are almost too many options for a premed student in Boston/Cambridge to start to make a list.
Someone above mentioned Colorado State. They do have a good music therapy program. For your daughter Colorado State would be ranked way lower than she could get into. However, one thing to think about is that Colorado State has a superb DVM program (ranked 3rd in North America, 4th in the world) and there will be very strong pre-vet students in the same premed classes (the required premed and pre-vet classes as far as I know are the same). Also, if you are from a WICHE/WUE state then Colorado State is a WUE school which might help with cost.
My take on the MA schools:
Berklee - Could be a dream for a kid really interested in jazz, but very specialized MT major. It’s not a BS or BA, but a BM (Bachelor of Music). Little math or science, but also so focused that it’s not your “typical” college experience. I’m not sure if that’s the best thing for a future therapist, but it’s a decision he’d have to make. And of course, there are dozens of colleges for your daughter in the Boston/MA/New England area. (Fun fact: We live outside of Boston and there are 3 flagship state universities closer to us than our own)
Ana Maria no longer offers a Music Therapy program.
Westfield State is a suitcase school. I wouldn’t recommend it for an OOS kid. Especially as there are much stronger MT programs out there.
For him, I think the major limitations will be jazz and his sister. If he’s making music that he loves, and has a job or volunteer role working with kids (this is really important to him, but he should be able to find it anywhere) and he can see his sister once in a while, he’ll be happy wherever. Suitcase or not, big/small, urban/rural he won’t really care. But a program that is narrowly focused classical music isn’t going to be great.
But the campus and the area around it will be super important to her. She would hate the suitcase school environment.
I suspect he would love Berklee. I can see it as his reach. If we went up there to visit, what schools would you suggest for her? Not tiny, urban but with a defined campus, safety or match for a likely high stats kid, decent merit. What fits those criteria?
You could also look at Cal State Northridge for your son, which would open up all of LA (UCLA, USC, the 5Cs (Pomona et al) although they would be a little farther away) for your daughter.
Reminder that Providence is within an hour’s train ride of Boston (inexpensive and frequent trains) so consider Brown for a high reach and the other Providence schools as matches or possibly safeties).
That’s a tough one. Lots of reaches that are expensive and offer little merit. Lots of small and rural. But defined campus, urban, safety/match and not too small is tough.
The state flagships would all have merit and be safeties (UNH, UConn and URI) but none are urban. Tufts, Brandeis, Northeastern, Brown are all reaches for anyone and wouldn’t have decent merit.
Emmanuel and Simmons would be safeties, are very small but in the heart of the city, have good access to the medical centers, and have good merit. (Both walking distance to Berklee as well).
I think Clark might be your unicorn (although small <3000 student). It’s in Worcester (up and coming, but still somewhat “gritty” city), decent merit, good teaching, very good research opportunities, an hour from Berklee. Holy Cross would check all of those boxes as well as long as you are okay with Catholic.
Providence College is another Catholic School that I don’t know a lot about but seems similar to Holy Cross and in Providence.
I keep coming back to Temple. I think Penn would be a reach she would probably love. Are there safeties and matches for her there?
Again, another state flagship with a great honors program, but not urban. UDel is only an hour away from Temple.
College of Wooster for him as well.
Though Temple would probably be a safety for your daughter, Temple honors would be a match. There are plenty of top students at Temple. My D17’s class valedictorian (1560 SAT) went to Temple in the honors program on a full tuition scholarship. I’m guessing both your son and your daughter would appreciate the diversity at Temple.
My high stats daughter graduated from UDel honors, got $17,000 in merit arch year, had a 3.9, and got accepted into every DPT program she applied to, is now at BU (with some merit). Reach schools were definitely not affordable for us.