Watchtower plays lots of games with definitions. Once they change a definition then they have a false assumption to build their deception on. Then they repeat the new definition and use its new meaning thousands of times to reinforce it. We all went through this indoctrination.
So, how do we untangle Watchtower deception? It's not that hard. Mostly common sense.
First of all, Jesus said that He was sent only to the lost sheep of Israel (Matthew 15:24)
In Jeremiah 50:6, God calls Israel His people and also calls them “lost sheep.” The Messiah, spoken of throughout the Old Testament, was seen as the one who would gather these “lost sheep” (Ezekiel 34:23-24; Micah 5:4-5).
So, when Jesus presented Himself as a shepherd to Israel, He was claiming to be the fulfillment of Messianic prophecy. This means that the sheep are Israelites. So, when Jesus said that he had "other sheep" not of this fold, he is saying that he is going to one-day shepherd non-Israelites as well.
The apostle Paul and others started gathering the other sheep (Gentile Believers) and made this announcement to them in Ephesians 2:14
But now in Christ Jesus, ye who once were far off have been brought nigh by the blood of Christ. For He is our peace, who hath made both one, and hath broken down the middle wall of partition between us, having abolished in His flesh the enmity, even the law of commandments contained in ordinances, that He might make in Himself one new man out of the two, so making peace, and that He might reconcile both unto God in one body by the cross, having slain the enmity thereby.
17 He came and preached peace to you who were afar off and to those who were nigh; for through Him we both have access by one Spirit unto the Father. Now therefore, ye are strangers and foreigners no more, but fellow citizens with the saints, and of the household of God.
Similarly, Jesus' brothers would mean first - his natural brothers. After that, the next meaning would be his countrymen - fellow Israelites. Thirdly, it would mean all his followers - Christians.
Now let's look at Mt. 25: 40
And the King shall answer and say unto them, Verily I say unto you, Inasmuch as ye have done it unto one of the least of these my brethren, ye have done it unto me.
The setting, when Jesus will say these words, is immediately after the great tribulation at the judgment of the existing nations. So who did Jesus refer to as his brothers?
1. His natural brothers is not an option. Because of the context, Jesus is referring to a larger group than his three brothers of his adoptive father Joseph
2. He could not be referring to Christians (believing jews and gentiles - "one new man") because the church has already been removed from earth and been raptured to heaven.
3. Jesus is referring to the rebellious Israelites who most of the nations had just tried to wipe off the face of the earth during the battle of Armageddon.
Remember that Jesus had just previously showed up with the Church from heaven (saints) and destroys the world's military attacking Israel with one word at Armageddon. Not much of a battle.
As a military mop up operation, Jesus now has a judgment to determine which ones of the survivors of the GT will be allowed to enter his Millennium Reign on earth. Each person will be judged on whether of not they supported the anniliation of Israelites (Christ's brothers). If a person supported the armies that he had just wiped out, they are not allowed in, and are sent straight to hell. If they did not support the anniliation of Jesus' brothers (his countrymen) - the Israelites, they are welcomed to enter the kingdom on earth.
This is the dominant evangelical view and is the simplest explantion.
Hope this helps.