Web Form - Filler selects CC

Hello, everyone! I've been using the Web Forms, and all the features are great. HOWEVER, I'd like for the Web form filler to be able to select who gets a CC of the form (agreement), once the signer/approver has finished the process. It has to be controlled, as I work in a school setting. Perhaps, creating a drop down with the email options, or adding a field where to enter it (granted that said email has our domain)? Or some other way. Is this possible?