Maybe I can help a bit (although I have also hit some road blocks in my research of the families). My wife is a descendant of Abner Hunsaker's brother, Nicholas Hunsaker and Rachel's sister, Olivia Montgomery Hunsaker. This is according to family notes. Abner and Nicholas were among 9 children born to Abraham and Mary Snyder Hunsaker.
Abner and Rachel apparently had 13 children. It is believed they married ca. 1823 and both died of cholera in July 1849. It is with the Montgomery connection where I have been stumped. I have been unable to connect Rachel, Olivia and two other supposed sisters (Rhoda and Susan) to any Montgomery. According to an obit for Nicholas and Olivia's son, Montgomery Hunsaker (my wife's gg gfather), Nicholas and Olivia came to Union Co. Illinois in the early 1800's from Kentucky and that Olivia's father was a surveyor from Kentucky named John Montgomery. I have been unable to confirm that any John Montgomery married and had children named Rachel, Olivia, Rhoda and/or Susan (or Susannah).
If you would like any oher info re: Abner and Rachel and their offspring, let me know and I will share what I have. If you have found any parentage for Rachel and her connection to Olivia, I would appreciate you letting me know.