Rodeo Merchandise Mail List

I have a roster that changes every time a pull it from a website. I am trying to track who has paid their dues and then send a bulk email to those that haven't paid. That part is easy, but we also allow extensions if the submit a google form - which is built and loads into a google sheet. As of now, I sort the roster by the "dues paid" column and paste it into the "unpaid" sheet. I need to find a way to import the data from the form entries and eliminate or merge that information into the "unpaid" sheet. The goal is to not have to manually remove all people with extensions so I can just copy/paste the emails to send a reminder.