My grandfather was Hall Edgar McAllister b. Jun e 13, 1885 and died March 18, 1964. His brother John Coumbs McAllister 1875-1948) who was married to Delia Bridget (Sullivan)McAllister. All my pictures of Hall McAllister was after he grew up. I would love to share info. I do not know anything about Decker McAllister. There were also other McAllister's in San Francisco including a famous Hall McAllister who I was told was an attorney (I have found no connection to him).
My branch of the McAllisters came from Bromley Township, Ontario, Canada. They were originally from County Antrim , Ireland. I have DNA results. We are R1b1a2(M 269)- one of the most common in Ireland and Scotland. Barbara McAllister Long