I know that Robert H. Allen is a brother to Jesse Allen of Mills River. I just don't know much about his family after the 1860 census.
Regarding Malvina Brock in the 1860 census with the Robert H. Allen family. She is the same age as Elvina Brock. She was a member of the Mills River Church. Elvina is a nickname for Malvina. The Mills River Church records list Joseph Kuykendall's wife as Malvina.