Looking for Nancy Jane

This past weekend, I spent part of my research time going page by page through the 1880 US Census, looking for any trace of my 3rd-great-grandmother Nancy Jane Flatt or her children (my 2nd-great-grandmother Mary Alice Cain or her brother Harl). They should be in Metcalfe or neighboring Barren County in 1880, but I can't find them. I looked through every page for both counties and turned up nothing. I may need to expand the search to the surrounding counties, such as Adair, where Nancy Jane's half-brother William was living with his young family. I may need to put this branch on hold for now, and focus my attention on another side of the tree.

"June" by Ellen Day Hale (about 1893)

Nancy Jane would have been 25 in the 1880 Census. Mary Alice would be 3 years old in the census, Harl should be under one year old. I don't know if Nancy Jane had other children before 1877. I do know that Nancy Jane married Pleasant Morgan in Barren County on 1 October 1884 using her maiden name Flatt. She would have been about 29 by then.