I have something to add. My interest was originally with the William Lell who has the Self's in his home in the 1880 census.
1) Willam Lell b. ca. 1837 married a Nancy Self. This info came from the Death Cert of their son William Henry Lell (1880-1961).
2) Nancy and Rachel Self aged 22 & 19 respectively are living with William and Martha Self in the 1870 Greene Co. census. Rachel's children, Perry and Francis who, based on the 1880 census would have been 1 year old, are not enumerated at all. But a check of the 1900-20 census's shows Perry consistently giving an age corresponding to a 1873/4 birth so the ages in 1880 appear to be off a bit.
It seems likely to me that the two children, Perry and Frances, were born out of wedlock.