Someone on the other thread suggested that singingdaughter start her own thread which seems like a good idea 
I always recommend that people read the Double Degree Dilemma essay written by David Lane, former head of admissions at Peabody, that is posted closer to the top of this forum. It really details the various ways to approach the study of music as an undergrad and does not just discuss double degrees.
I wrote a response to a parent asking about composition on the same topic, combining music and another area of study, which you can also read but I will write some of the same things here.
At most schools there is no such thing as “prelaw.” You can major in most things, including music, and can go to law, medicine, nursing or any other professional or grad school- as long as prerequisites are done (and they can be done postgrad if necessary). You probably don’t want to plan things according to that goal anyway, since things change.
People are recommending colleges/universities that have conservatories or schools of music. That is a great idea if she wants to do a double degree, which is usually 5 years.
If, however, she wants to do a double major or music and something else, she might be well-served at a college or university that does NOT have a conservatory or school of music.
As you can tell, you really need to look at every school in detail.
I think she needs to clarify what she wants: double degree, double major, major.minor, or studying something else and doing music as an extracurricular (with lessons and extracurricular performance). A BM is intensive music with 2/3-3/4 classes in music and a BA is 1/4-1/3 classes in music (plus gen eds if required).
It is okay to apply to several options and decide in the late spring of senior year.
If she applies to a non-audition school, she would do a music supplement to the common app with a recording, music resume, and recommendation letters from music teachers or directors.
It is possible she could consider Ivies and other selective schools, which have great financial aid, if money is a problem. A music supplement from a talented student can help a lot with admissions. (Harvard also has a double degree program with NEC, as does Tufts).