Did not Sister White remain in the large Seventh-day Adventist Church until her death?

Answer:

Yes! But at the time of her death on Friday, July 16, 1915, America had not yet entered the war. The United States joined in the war effort in 1917, two years after Sister White died. So the test concerning the war question had not even developed in America, for which reason Sister White had no occasion to make any special comment or decision beside her printed testimony. When someone inquired about the European situation and what to do, she is supposed to have said, “I think the brethren should do their duty, ” which can be interpreted in any way.