Adding a subscriber to 2 list at the same time

Hi, is there a way to add a new subscriber (registered via a third-party sign up form on our website) to 2 lists on sendy instead of just 1?

Eg: A new user signs up on our WordPress site via Gravity Form plugin. It is connected to "List 1" in our sendy account. However, is it possible to also add the subscriber to "List 2" along with "List 1".

Any help is appreciated. Thanks!