1. Both the National Archives and www.civilwardata.com list a William Bryant in Company I, VA 47th Infantry. He enlisted on 6-16-61 as a private, and deserted 3-29-62. Civil War Data's source is the Virginia Regimental History series of books(on all of these soldiers).
2. CWD.com list a William Bryant in Company A, VA 47th Infantry, enlisting as a private on 4-25-61. He is not listed in the Archives, but the VA State Library indicates he served to the end of the war.
3. The Archives have a William H. Bryant as a private in the VA 47th, Company A. This listing is not in CWD.com. Is this the same man as #2?
4. CWD.com list a William H. Bryant, from Stafford County, in the VA Stafford Light Artillery. He was a 22 year old laborer,and is listed in the 1910 census of Stafford County VA as widowed, age 72. This listing is not in the Archives.
My guess is these records detail 2 or 3 men, not 4. The most detailed info is #4; I'd check with the VA archives, as well as the state library, to see if he requested or was given a pension, as pension data usually gives family details. Also check both sources for info on the other participants.
Good luck with your search!! Bill