confirm to or confirm with

I was sending a mail from my office to a few people inviting them to a party. I wanted to tell them to tell my P.A whether they shall make it or not. However. I couldn't construct a proper setence.
Ismit correct to say. Confiirm your attendance to Amy. How different is it from confirming it with Amy. To or with, which do I choose.

Thanks in advance. :-)