Conditional Emails and hidden fields

Hi,
We’ve got form maker pro + conditional emails plugin.
On one of the forms I have a hidden field that I set its value dynamically according to user parameters.
I just found out that on the conditional emails settings tab, I don’t have the hidden field on the list. I can set the emails only by the visible fields.
Why don’t I have the hidden one on the list too? I need to send the form to different mails according to the hidden field’s value.

I know I can have that field visible and hide it with css, but it doesn’t make sense it is not there on the list for me to use. I prefer it will be hidden from the beginning to avoid seeing it by mistake if css fails for some reason.
Can you please fix that?

Thanks,

Yael