I don't know how much help I can be, but I always love looking into Farmerville, in Union Parish since my 2nd great grandmother & 3rd great grandparents were from there. Yay Farmersville! :D
I've only done a quick search so far, but the one person I seem to find the easiest is Abbie G. Davis, who you have a few census records for.
So in that 1900 census, Abigail "Abbie" is married to Charles "Charlie" Davis..
On that 1880 census when it shows Abbie as 30, it does show her name as Dans, but its looks like that was a typo because someone sent in a correction saying that the spelling of Dans should be Davis.
Also on that 1880 census, Abbie & her husband Charlie Davis appear to be living with her parents, Mariah and Edward Willis. Mariah has a sister who is widowed, Mary Hendrix, also living with them. (Hendrix would be Mary's married name)
It looks to me like Charlie and Abbie's children were:
01. Samuel Davis, born in 1867
02. Ellen Davis, born in 1869
03. Martha Davis, born in 1871
04. Emma Davis, born in 1873
05. Sallie Davis, born in 1875
06. Holly Davis, born in 1877
07. James Davis, born in 1879
08. Paul Davis, born in 1887 (twin)
09. Pauline Davis, born in 1887 (twin)
10. Baker Davis, born in 1888*
11. Jobe Davis, born in 1889
12. Charlie Davis, Jr., born in 1890
13. Lizzy Davis, born in 1896
* the census shows Baker's birth date as 1889 (same as Jobe's, but since he was a year older than Jobe, it had to be 1888)
In that 1910 census where Abbie is now widowed and 57 years old, she now has a granddaughter also living with her, Lela McElroy, but I'm not sure which of Abbie's daughters Lela was. Maybe you know all this? :)
In that 1910 census, it looks like Abbie is running the family farm with the assistance of some of her children still living with her, along with a female boarder by the name of Easter Heard, age 45.
But it sure looks like your first hunch is right that Emma was one of Abbie's daughters. :)
I hope I didn't confuse things! I love researching that area of Louisiana since I also have so many family members from there.
Take care! Sherry xoxo