I have Sarah Amy as the daughter of Benjamin Hasty and Lydia Dugger as well, but I show that Benjamin Hasty (Sarah's brother) died in Smallpox Hospital, Memphis, Tennessee. I don't have a date of death for him, though.
If the massacre story is true, other of Sarah's siblings seemed to have survived as well..
Brother Joseph married Melinda Caroline Galtney. He had at least one son, James Jordan Hasty, born 26 Feb 1852 in MO. James went on to marry Lucinda Schrum on 2 Feb 1873 in Reynolds Co MO. Their daughter Lucinda married Edward B. Depew.
Brother Ephraim married Martha Endry Merricks on 6 Jan 1866 in Iron Co MO and had at least one daughter, Mary Jane Luello Hasty, born 29 Oct 1866. Mary Jane went on to marry Alfred Henry Bonds and have at least 5 children.
The story is interesting though, and I've filed it for further research... But I did want to check with you to see if my information matched yours... let me know..