Anonymous wrote:OP here.
Senior year she is allowed to take multivariable or AP stats.
The school won't allow calculus BC after AB as they view it as a review of material and too easy following AB (an easy "A"). They are firm on this. She's doing very well in AB (it's an easy course.)
Clearly she is not aiming for MIT or similar.
AP Calc BC, aka Calc 2, is a prerequisite for any actual college multivariable Calc class. If this is the high school's own multivariate class, the policy does not reflect well on the course.
I would talk to the multivariable teacher and see if they might be an ally to help advocate for your daughter's need to take BC senior year.
If the school does not budge, I would look at dual enrollment Calc 2 over the summer, which is likely to be fine, a doable workload even with a summer job.