The problem with viewing Watchtower's writings being part of the bible is that eventually you have to rip out old pages from the "bible".
In 1981, anyone that felt the Slave did not include ALL the 144,000 were described as indulging in "self-deception".
"The objectors may argue that not all of Christ's anointed disciples have a share in preparing the spiritual food, so that perhaps the "slave" pictures only the leading ones, and the "domestics" those they serve in the congregation.
There is no point in trying to force an interpretation of the parable. Self-deception is of no benefit and is spiritually damaging. ... Thus we see a clear Scriptural basis for saying that all anointed followers of Christ Jesus make up God's "servant," with Jesus as its Master." Watchtower 1981 Mar 1 pp.24-26
But just a few years later, what was once self-deception and "part of the bible" had to be ripped out when they said just the opposite and claimed the GB were the F&DS.
""Who Really Is the Faithful and Discreet Slave?"
... From 1919 on, there has always been a small group of anointed Christians at the world headquarters of Jehovah’s Witnesses. They have supervised our worldwide preaching work and have been directly involved in preparing and dispensing spiritual food. In recent years, that group has been closely identified with the Governing Body of Jehovah’s Witnesses." 2012 Annual meeting jw.org 10th Nov 2012.