Is This Legal?

Nationwide offers a great price online. However, AFTER they obtain your financial information to draft payments, they add things to the policy causing the premium to sky rocket.
They added my daughter to the policy without my knowledge. My daughter is 30 years old, married for 5 years, living in her own home with her husband and 2 children. She has not lived with me, nor been on my policy for nearly 10 years. However, Nationwide added her, which made my premium increase over $500 for six months.
When I contacted Nationwide about this, they are requiring that I send them documented proof of my daughters current residency. Otherwise, nothing can be done. I have to provide them with her mortgage information, copies of utility bills, and copy of her driver's license.