Trying to redeem netflix offer. Email used for promo and email on netflix are 2 different ones. How do I redeem?

Do I have to change the email on my netflix account? That would screw my whole family up as we all use the same account and everyone knows the username and password at this point and that would be confusing.

I had to use my mom's email as she is the primary account holder and the upgrade was done under her name for that reason. The netflix account is mine therefore the emails are different. I'm entering my email and it keeps saying "Email or confirmation id" is wrong. I'm assuming it is because it doesn't match my mom's email.

Is there any way I can redeem this without having to change my netflix email?