If you don't know how to add alternate email id on Yahoo then for the guidance you can read the articles and blogs related to the same. If after reading the blogs and articles you are not able to add the email id on your Yahoo account then just avail
Yahoo Customer Service by making a call at 1-833-554-3444. You can contact the provided number whenever you want as we are accessible all the time to provide the best customer care service.
https://www.contact-customer-service.co/contact-yahoo/