I have information on your Howard family. First of all, William and his siblings were not born in Alabama, but in Louisiana. His father, Hardy Howard, was in LA as early as 1850. He is listed on the 1850 Union Parish Census as a 22-year old overseer for Johnson Malone. He is shown as being born in Alabama. By 1860, Hardy is married to Nancy and they are living in Union Parish. He is still an overseer. Hardy is shown on the 1867 Voter Registration list for Union Parish.
By 1870, Hardy and Nancy have three children, Jane, another female and James [age 3]. James would be your William since in 1880, he is listed as William J. H. Howard [age 12]. In 1880, Hardy and Nancy are both listed as having been born in AL. Hardy's parents are also shown as being born in AL. There are seven children listed: Giney , William J.H. , John H. , Caroline L. , Robert L. , George A.  and Arrena ? [5 months].
In 1900, I found Willie Howard [bn 9/1867] m. 14 years. His parents are shown as being born in LA, which is not correct. Mary is shown as being born in 1867 and as having had 7 children/all still being alive. The children were: Hardy, Barnie, Rilla, Eliza, Cora, Oda and ?. Nancy, the mother [bn 4/1845], is living with the family.
You can find the census records:
1850 - Hardy Howard
1860 - H. Howard
1870 - Hardy Howard
1880 - Wm J H Howard
1900 - Willie Howard
All the census records are in Union Parish. The 1860 census has Farmerville Post Office. The 1870 census has Marion Post Office. The family seems to have moved around the parish.
I hope this helps with your research. Good luck.