When you purchase a new GoPhone Plan with AT&T, you can link up to two users on your account to receive multi-line discounts each month.
Once you have purchased the plan you’ll need to follow the activation process to get started. Once you’ve activated your new plan, you can log into your AT&T online account. Here you’ll find a button to send the request for multi-line discounts.
Simply select the button to send the request to link. You’ll be prompted to enter in the phone number of the person to link. Once the person accepts you will get $5/month discount.