Hello Rick
You are correct; it is not possible at present to specify which email address to send the workflow email to; it will go to email address 1. You could potentially work around this by having a series of update steps in the workflow that rearrange the email addresses for sending purposes, then move them back to their original fields. If you decided to look into that option, you would need to be careful that you set it up in such a way that none of the email addresses are overwritten by the others, and you may also run into the issue of trying to send non-workflow emails to the person while the email addresses are rearranged.