I don't have proof that my great-grandmother, Nancy C. is Parthenia's sister - but some documents I have do seem to connect them. The census you mentioned was the 1880 one with Nancy C. Hopkins being a widow with two children. It shows her age as 35 yrs. old which would give her birth year at or near 1845. The Madison CO MO census of Pleasant Moore's daughter Nancy showed age 5 yrs.
After Walker (not Walter) Hopkins died in Feb. 1880, Nancy married John Gooch that same year. She died in 1886 and record shows she was buried at Hamtown Cemetery (same place as Pleasant Moore). Various records have his name as Plaze, Pless and Pleasant.
I have a copy of a picture of Fred Moore given to Emma Moore and he looks to be about 14 yrs old. On the 1900 Butler CO MO census I see that Burt had a son named Frederick who was 12 yrs. old at that time.
As I said before, Harvey Moore and Emma Frances Hopkins married at the home of W. H. B. Moore at Blackriver Twp. in Butler CO - so I believe there is a definite relationship with Pleasant Moore family and "my" Nancy C.
Some surnames I have found on family documentation are: Sliger, Metcalfe, Epps, Jonas. Are any of these "yours"?
It is not helpful to find various spellings of names. I've found a marriage recorded between Parthena E. Moore and James C. Thomas, birth register showing Parthenia E. Moore Epps, and Partina Moore on the 1850 Madison CO MO census.