jnpope: I'm not sure if Sedgwyn is a phonetic pronunciation of Séguin or if he changed names for some reason when he left New Orleans, but here is what I was able to dig up:
<SEGUIN-On Tuesday, Nov. 28, 1916, at 3 o'clock p.m., in Brooklyn, N. Y., JAMES DE BENNEVILLE SEGUIN, aged 63 years, a native of New Orleans. Interment in Brooklyn, Friday morning.
<New Orleans Times-Picayune, 1916.11.29, p2>>
<John [sic] D. Sedgwyn 57 [sic] years old, of 387 Clinton street, for eleven years a proofreader with The Eagle, and for several years a chess expert for Southern newspapers, died yesterday afternoon at his home, after a lingering illness. Mr. Sedgwyn was born in New Orleans, La., son of Dr. James T. Sedgwyn, a prominent physician of that city. He came to Brooklyn about twenty years ago and had lived here ever since. He is survived by his widow, Laura T. Sedgwyn. The funeral services will be held Friday morning, with a requiem mass in St. Stephen's R. C. Church. Hicks and Summit streets, interment following in Holy Cross Cemetery.
<Brooklyn Daily Eagle, 1916.11.29, p3>>
<A requiem mass was celebrated in St. Stephen's R. C. Church to-day for John [sic] D. Sedgwyn, 57 [sic], who died Tuesday at his home, 387 Cliton [sic] street. Interment followed in Holy Cross Cemetery. Mr. Sedgwyn was for eleven years a proofreader on the Brooklyn aDily [sic] Eagle and for sometime a chess expert for Southern newspapers. He was born in New Orleans, the son of Dr. James T. [sic] Sedgwyn, a prominent physician of that city, and came to Brooklyn about 20 years ago.
<Brooklyn Times Union, 1916.12.01, p8>>
The family history goes something like this:
André Séguin (grandfather, shipyard builder in New Orleans)
Dr. James F. Séguin (father, b. 1815.11.23 Philadelphia; d. 1890.12.20 New Orleans, obit: Times-Democrat, 1890.12.22, p3)
Four sons all survived the death of James F. (of which two were chess players):
James D. Séguin (b. 1853.09.11 New Orleans; d. 1916.11.28 Brooklyn)
André William Séguin (brother, b. 1866.02.24 New Orleans, d. 1932.07.13)
I have yet to confirm the identity of the other two brothers...
Now James D. Séguin married Laura Templeton Harvey (b. 1854.06.10, d. 1940.07.27) and had two children:
Louise Maria Séguin (b. 1878.06.21 New Orleans, d. 1944.10.08 New Orleans)
James D. Séguin Jr (b. 1879.06.21 New Orleans, d. 1940.07.22 five days before his mother)
Both Louise and James Jr played chess and Louise even helped with the Times-Democrat column according to the ACB:
<<thomastonk:> According to Gaige's "Chess Personalia", James DeBenneville Séguin died on November 11, 1916.>
My copy says 28-11-1916... which matches the historical record.