My wife's great-great-uncle was an Elmer St.-AMAND born in October 1881 in New York. His father was Henri Alexandre St.-AMAND, sometimes also known as Pierre or Peter, and his mother was Sarah Elizabeth ACKERMANN, married Dec 1, 1880 in Manhattan. I have no record of a twin named Henry. The father Henri was born in Quebec in 1850. You can find the family living in Paterson, NJ on the 1900 through 1930 Census, with the father cited as Peter A. St-AMAND.
The names of the parents of Henry Alexandre (Pierre/Peter) St.-AMAND are not very legible on the enclosed certificate of marriage to Sarah ACKERMANN, but might be Lucien and Arminia St.-AMAND. Her parents are James ACKERMANN and Elizabeth HOFFMAN. I have had little success tracing either family back further.