Thanks for your question.
The Seventh-Day Adventist so-called prophetess, Mary-Ellen White, is just one of a number of false prophets who arose in the 1800s establishing their own churches on their own authority. Other churches established about the same time by so-called "prophets" were the Jehovah's witnesses, the Mormons, Christian Science, and the Baha'i movement.
Forget the ramblings of this false prophetess and stick to the Bible. We do not need new prophets preaching a different gospel than that which the apostles preached. See Galatians 1:6-9. The only biographies we need to pay attention to are those contained in the pages of the Bible, both Old and New Testaments. Mary-Ellen White is a false prophetess claiming divine inspiration when she has none. She will have much to answer for when the Lord returns.
I hope you have found this helpful.