I don't have a copy of Owen Co. Cousins myself, but I am familiar with the Fiscus families.
The obituary is a little bit inaccurate, which is probably why you are having trouble locating Susannah's family. She is the daughter of John Henry Fiscus from his first wife Elizabeth Childress (the youngest surviving - I don't know if there were any younger children which died young). They actually didn't move into Iowa until after the 1860 Census, first settling in Greene County (where they were in 1870) and then moving to Harlan, Shelby County by 1880.
John Henry Fiscus is the son of Frederick, son of Adam, son of Frederick (original immigrant in 1743 on the Loyal Judith). [Please note that I'm only listing the names they went by, and not their full names.]
John Henry had a second family after Elizabeth passed away with Polly Conrad.
You can see Susannah Brockaway in the 1925 Iowa State Census which confirms her parentage.
I hope this helps,
Trevor Carlson
Edmonton, AB