Donna,I just got through reading the discussion on the Mills Genforum site.Are you a Mills researcher or a HOrseman researcher, or both?
I have three Julia A. Horsemans.One is the daughter of John and Sarah (for which you cited the 1850 census record.)
Another one was born abt 1812 to Stephen and Mary Horseman in Loudoun Co, VA, 6th of eight children.Stephen is a son of William who married Helen Ellender Lay, referred to in one of the discussions on the Mills forum.
The third one is the 6th of 10 children born to James and Mary E. Horseman, born about 1841.James was b aboout 1806, but I do not know his parents.
Do you happen to know anything about the other two Julias?