How can I allow responses to be emailed to a third party?

Assuming you already have an email address field in your form that will be filled by your respondents

and you have also set up an email autoresponder that will be sent to the email address your respondents entered in that email field.

From what I understand, you would want to have a copy of that email autoresponder to be sent to another email address that will be provided by your respondents in another email address field in your form.

You have two options to achieve your requirements.

1. Create a copy of the email autoresponder in your form and set the "Secondary person email address" field as its recipient.

2. Send the "same" email autoresponder to both respondent and secondary person's email address using conditional logic.

We will be applying the same idea that is explained in this guide — How-to-Send-Email-Based-on-User-s-Answer

With this option, you will only need to set up 1 email autoresponder in your form.

To begin, please take note of the field name or {questionName} of both the email address fields in your form. How-to-Find-Field-IDs-and-Names

You can find that information under the "Field Details" section of the Advanced tab when you view the field's properties.

In my example, it will be {respondentsEmail3} for the Respondent's email address field.

and {secondaryPerson}  for the Secondary person email address field

After that, you can not create the condition that will send the email autoresponder in your form if any of the email address fields in your form is filled.

I hope this helps. Please give both options a try and choose which will best suit your needs.