Willis Daniel Sedwick  [George W Sedwick / Caroline Reeble]
(AKA Daniel Willis Sedwick)
b. November 13, 1860, New Castle, Lawrence, Pennsylvania11f
d. October 6, 1935, Montrose, Lee, Iowa11f  obituary
bu Rock Island, Rock Island, Illinois11f
m. December 5, 1883, Aledo, Mercer, Illinois, Betsy Armina Green11f,4 (vol 1 pg 76)
Member of the M. E. Church

Betsy Armina Green  [Daniel Green / Amy Dewitt]11f
b. February 6, 1857, New Windsor, Mercer, Illinois11f
d. September 23, 1920, Rock Island, Rock Island, Illinois11f
m1 unknown Tonkinson4

Census records:

1870 IL Mercer, Suez Twp
1880 IL Mercer, Suez Twp
1900 IL Henderson, Lomax Precinct
1920 IL Rock Island, Rock Island
1930 WI Grant, Mount Hope

I believe that Willis Daniel Sedwick AKA Daniel Willis Sedwick
is the Samuel W Sedwick son of George W Sedwick in the 1870 census,
but that Daniel was misunderstood and (very clearly) written as Samuel.

Children:

George Washington Sedwick1
  b. August 15, 1886, Viola, Mercer, Illinois11a,1 or Broken Bow, Custer, Nebraska11f
  d. February 23, 1962, Nora, Jo Daviess, Illinois11a
  d. aft 193518
  m. February 13, 1911, Ruth Tillie Gimson11a
Effie Sedwick1
  b. February 23, 1889, Broken Bow, Custer, Nebraska11f
  d. bef 1935?18
  m. February 26, 1907, Saint Louis, Saint Louis, Missouri, Charles Clinton Knowles11f, 11g
Minnie A Sedwick1
  b. April 24, 1891, Broken Bow, Custer, Nebraska11f
  d. aft 193518
  m. March 20, 1910, Saint Louis, Saint Louis, Missouri, William J Mears11f
Amy Gwendolyn Sedwick  [Willis Daniel Sedgwick / Betsy Armina Greene]
  b. June 12, 1894, Eding, Knox Missouri11f
  d. November 30, 1928, Mount Pleasant, Henry, Iowa11f
  bu December 3, 1928, Rock Island, Rock Island, Illinois11f
  m1 July 1, 1912, Quincy, Adams, Illinois, Milo Herbert Judevine11f
  m2 January 28, 1919, Mount Pleasant, Henry, Iowa, Floyd Murdock11f
Willis Daniel Sedwick11f
  b. March 24, 1896, Eding Knox, Missouri11f
  d. October 2, 1920, Rock Island, Rock Island, Illinois11f
Bettie Valentine Sedwick11f
  b. February 14, 1898, Dallas City, Hancock, Illinois11f
  d. bef 1935?18

Obituary of Willis Daniel Sedwick18 in 1935 said he had a surviving daughter Ms W F Murdock of Washington, Iowa. Murdock's wife Amy Gwendolyn Sedwick is reported to have died in 1928, and in the 1930 census he reports he is widowed. Is it possible that he married one of her sisters?

Sources:

1. Census records, any of those indicated.

4. Illinois Statewide Marriage Index 1763 - 1900
online at http://www.cyberdriveillinois.com/departments/archives/genealogy/marrsrch.html
This record:
GroomBrideCountyDateVol/pgLic
Sedwick, Willlis DTonkinson, Mina Green (Mrs)Mercer12/05/1883001/0076004873.5

8. Mercer County, Illinois Cemetery Records
William Dennison Chapter, NSDAR, Aledo, Illinois, 8 volumes
available on LDS Microfilm 0848589 for Volume I and 0848590 for volumes II through VIII available online at US GenWeb, Illinois, Mercer

11. Personal knowledge of family members
a. Effie "Pat" (Sedwick) Longerbone, daughter of George Washington Sedwick
b. Lyle D Sedwick, descendant of Dan W Sedwick
f. Catherine Kimmell, descendant of Daniel Greene and Amy Dewitt
g. Jana Knowles, grand-daughter of Charles Clinton Knowles and his second wife.

18. Obituary of Willis Daniel Sedgwick
said to be from a Lee County, Iowa, newspaper
scan sent by Catherine Kimmell, related to his wife Betsy Green

Questions? Have more data? genealogy@sedgwick.org