A poor family decided to go west and had to leave one of the daughters behind, as she was sick. They left her with a husband and wife. Her family was killed in a flash flood. She stayed with the couple, they are involved with the underground railroad
Stump the Bookseller
New format, same book stumper solving.
Maybe “Voices in the Night” by Rhoda Warner Bacmeister?
The Aldens had taken Jeanie in after her father had died at the beginning of the Civil War, but there was something strange going on at the farm.
https://www.goodreads.com/book/show/3986953-voices-in-the-night
This is the book! Thank you!