You can cover how the Divine name was definitely NOT in the Greek scriptures.
You could evern use WTS stuff to show why they thought it should be there, then
discuss whether it should be there or not. Regardless of their reasons, it is easy to
show how they wanted the scriptures to retain their original intent, and putting the
name in where the writer probably did not (you could say definitely did not) is
changing the intent of the original writing.
You could discuss how it wouldn't be so wrong to properly address God by his
title. We show respect to titled people by addressing them by their title-
Mister President, Your Majesty, Senator Smith, Doctor Jones. We would not
call our earthly father Bill or Ted, so what's wrong with other religions saying
Our Heavenly Father or God instead of Jehovah?