I also have no experience with Broadway Dance Center, but here is the link to their international (visa) program: http://www.bwydance.com/isvp/about.shtml
It does seem that these students tend to be in their twenties.
STEPS on Broadway has a visa program, but only for those 18 and older.
Unless your daughter is an American citizen, she will have to have a visa to study in the US (unless it's just for a summer program). And given the ever changing situation with student visas in the US, and time & money it takes to obtain one, I would encourage you try and find someone in Paris with experience in these issues. Perhaps there is someone at one of your daughter's current schools who has studied abroad or an organization that assists students in finding foreign study programs.
You might want to look into summer programs.
You might also want to consider London...I don't know what might exist there in terms of jazz programs, but I would imagine that there might be some good programs there.
A couple of sites that may help:
The US Government site on student visas
EduPass, which focuses on university level programs, but seems to have plenty of good info: www.edupass.org