Form for Mainpage Link to Main Email Sign Up page

We have a basic email sign up form on the our main page that just collects the email address (we’ve temporarily adding in the First and Last Name as well) but when those Leads get created with only the email address it’s a problem for us… since we need that other information.

Our main email sign up page has a much more extensive form: https://www.conservationnw.org/take-action/email-signup/

Is there a way to have the form on our mainpage, that just has the email field, send new sign ups to the email sign up page with the email already auto populating that field on that page?

Thanks!
Matt

The page I need help with: [log in to see the link]