Passing Extra WordPress Registration Data to Mailchimp

Hi,

I am using Register Plus Redux to add extra user fields to my WordPress Registration form. I am also using a Mailchimp for WordPress checkbox on the Registration form so that the user data is then passed to my Mailchimp list. Unfortunately the data in the extra fields added to the Registration form using Register Plus Redux does not get passed to the Mailchimp list, only the standard First Name, Surname and Email address does.

Does anyone know how I can go about achieving this?

Many thanks,

Richard.

https://www.ads-software.com/plugins/mailchimp-for-wp/