The other groups broke away from them -- like the 3rd generation of reformatters included the Unitarians (in the 16th century) and the Wesleyans (in the 18th century) and the anabaptists (in the 16th century)
the Baptists broke away from the Anabaptists in the 17th, making them 4th generation reformatters
The fifth generation include the radical reformatters like the Christian Scientists and then the really weird groups like the Seventh Day Adventists, Jehovah's Witnesses and Mormons -- arguably, even though the latter 3 came from this 5th generation mileieu they are arguably not Christian
The 6th generation included the pentecostals
And now the 7th are the Word of Faith pentecostals and the Oneness pentecostals (those who deny the Trinity)
only the Lutherans, Presybterians, Reformed and Anglicans are really the "Protestants". All others are simply their own traditions or splits from those 3 traditions
Do tell why you think SDA’s aren’t Christian? They don’t worship Jesus’ mother or bow down to graven images like the Catholics; these things alone disqualify CATHOLICS not SDA’s