Here is his parents' marriage:
<ref>"New York, New York City Marriage Records, 1829-1938", database, {{FamilySearch Record|Q2CX-QC91}} (17 August 2022), Henry Douglas Mackintosh and Amelia Kline, 1906. Henry Douglas Mackintosh, age 29, father Walter Scott, mother Isabella Binning. Amelia Kline, age 25, father Adam, mother Kate Furrer. Married 28 March 1906 in Queens, New York City. Accessed 13 October 2022.</ref>
Direct link.