Make new local admin user account a member for the default administrator's group

Hello,

I have followed the steps in the link below to create a  GPO with a new local admin user account and have disabled the built-in admin account.  I need to be able to make the new local admin user account a member of the built-in administrator's account just like the original "Administrator".  What is the best way to do this?

http://www.dannyeckes.com/create-local-admin-group-policy-gpo/comment-page-1/#comment-2829

Thanks,

Roger