I did some more digging into the Valentine (paternal) side of the family. I am posting what I found in terms of related family names - maybe a fellow Unclaimed Team volunteer's resources will uncover something?
It seems like the unclaimed's father was an only child and his mother was an only surviving child after the death of the maternal uncle during WWII so I don't know if first cousins are likely here. The only remaining direct relative possibility seems to be the older sister, Annie Valentine, who is mentioned in the maternal Grandfather's (Einar Vorm) census.
Aside from that, it looks like we may have to research relatives extending from the grandparents, either maternal or paternal.
Henry Walton Valentine, Sr. (Unclaimed's Paternal Grandfather)
Wife: Clara Valentine
Children: Only one found in census listings: Henry Walton Valentine, Jr.
Mother's Maiden Name: Possibly Badell (see below)
Possible CDI Listing
"California, Death Index, 1940-1997," Henry W Valentine, 1946
name: Henry W Valentine
event: Death
event date: 28 Nov 1946
event place: San Diego, California, United States
birth date: 27 May 1881
birthplace: New York
gender: Male
father: Valentine
mother: Badell
Henry Walton Valentine, Jr. (Unclaimed's Father)
Wife: Eina LaCour Vorm
Children: Annie Valentine, Henry Walton Valentine, III
Father: Henry Walton Valentine, Sr.
Mother: Clara Valentine
Mother's Maiden Name: Unknown
Father-in-law: Einar Vorm
Mother-in-law: Christa Vorm (other variations including Christie)
Brother-in-law: Eldon LaCour Vorm
Henry Walton Valentine, III (Unclaimed)
Wife: Unknown
Children: Unknown
Father: Henry Walton Valentine, Jr.
Mother: Eina Valentine
Mother's Maiden Name: Vorm
Siblings: Annie Valentine
Information the team might find useful
Unclaimed's Grandfather's Household in 1910 Census
"United States Census, 1910," Henry W Valentine in household of Henry W Valentine, Newark Ward 16, Essex, New Jersey
name: Henry W Valentine
birthplace: New Jersey
relationship to head of household: Son
residence: Newark Ward 16, Essex, New Jersey
marital status: Single
race : White
gender: Male
immigration year:
father's birthplace: New York
mother's birthplace: New Jersey
family number: 258
page number: 10
Household Gender Age Birthplace
self Henry W Valentine M 28y New York
wife Clara Valentine F 26y New Jersey
son Henry W Valentine M y 2m New Jersey
Unclaimed's Grandfather's Household in 1920 Census
"United States Census, 1920," Henry W Valentine, , Westchester, New York
name: Henry W Valentine
residence: , Westchester, New York
estimated birth year: 1882
age: 38
birthplace: New York
relationship to head of household: Self
gender: Male
race: White
marital status: Married
father's birthplace: New York
mother's birthplace: New York
film number: 1821279
digital folder number: 4442109
image number: 01092
sheet number: 9
Household Gender Age Birthplace
self Henry W Valentine M 38y New York
wife Clara Valentine F 35y New Jersey
son Henry W Valentine M 9y New Jersey
Unclaimed's Grandfather's Household in 1930 Census
"United States Census, 1930," Henry Valentine in household of Henry W Valentine, Yonkers, Westchester, New York
name: Henry Valentine
event: Census
event date: 1930
event place: Yonkers, Westchester, New York
gender: Male
age: 20
marital status: Single
race: White
birthplace: New Jersey
estimated birth year: 1910
immigration year:
relationship to head of household: Son
father's birthplace: New York
mother's birthplace: New Jersey
enumeration district number: 0014
family number: 236
sheet number and letter: 12A
line number: 6
nara publication: T626, roll 1666
film number: 2341400
digital folder number: 4638880
image number: 00996
Household Gender Age Birthplace
head Henry W Valentine M 48 New York
wife Clara Valentine F 45 New Jersey
son Henry Valentine M 20 New Jersey
Unclaimed's Grandfather's Household in 1940 Census
Note: Unclaimed's father is no longer listed and shows up under maternal grandfather's census listing (see previous post)
"United States Census, 1940," Henry W Valentine, Ward 3, Yonkers, Yonkers City, Westchester, New York, United States
name: Henry W Valentine
titles & terms:
event: Census
event year: 1940
event place: Ward 3, Yonkers, Yonkers City, Westchester, New York, United States
gender: Male
age: 58
marital status: Married
race (original):
race (standardized): White
relationship to head of household (original):
relationship to head of household (standardized): Head
birthplace: New York
estimated birth year: 1882
residence in 1935: Same Place
enumeration district number: 68-17
family number: 81
sheet number and letter: 3B
line number: 67
nara publication number: T627
nara roll number: 2863
digital folder number: 005459468
image number: 00484
Household Gender Age Birthplace
head Henry W Valentine M 58 New York
wife Clara Valentine F 56 New Jersey