The JWs did not add Jehovah to the New Testament they just followed other bibles mostly that did this already. Some bibles add it even more then 237 times.
The original poster has come to a very odd conclusion. With 66 books in the canon you have many views of god.
I would recommend before you get hung up on Jehovah's name check out 'Yahweh' on Wikipedia (and check the sources at the bottom!) and find out where Yahweh came from....The Shasu tribe.