The Hallam brothers had a sister JANE HALLAM, per David Hallam’s obit.
(Logansport Weekly Recorder 25 November 1912): “David Hallam, age seventy-three years, residing at 1728 Knowlton Street, died Sunday night at 11:30. He was the son of Moses and Lavina [sic] Hallam, and leaves one son Frank Hallam, of this city; one sister, Mrs. Jane Hinkle of Greentown, Indiana…” (posted on the online family tree, see above LINK).
This could be Mathew. 1910 Vernon County, Missouri Mathew Hallam 74 Sarah Hallam 62 Charley Hallam 32 Oscar Hallam23 Harry B Hallam21 Etna J Hallam20 **check into burials at Green Lawn Cemetery, Schell City, Vernon, Missouri