Yes he did have a brother named William. But there is spme discrepency on birth dates. Here is what I have on the both of them:
WILLIAM, born April 10, 1840, died Sept. 14, 1862.
Andrew F. Trumbo was born in Kentucky about 1827. He married a Mary S. Flournoy 22 December 1859 in Linn County, Missouri and they had three children. She was born about 1842 in Missouri. Isaac Trumbo said, "He owned land in Linn County, Missouri. He worked for Waddell Majors Fargo, a big company at Independence, Missouri. They ran ten thousand wagons for the government contractors in the west. He took thirty wagons over the plains at a time for a salary of eight hundred dollars. He told me he was so clever he gave all of it away." At one time he lived near Barrs Ridge, California. They lived in Linn County, Missouri in 1860.