See also

• William Underwood's parents: Richard Buswell Underwood (1827-1904) and Harriott Marshall (c. 1855-1944)
• William Underwood's siblings: Richard Charles Underwood (1874-1920), Alice Underwood (1875-1955), John Underwood (1876-1898), George Allan Underwood (1879-1964), Clara Underwood (1880-1956), Arthur Underwood (1883-1938), Maria Underwood (1885-1973), Francis Underwood (1886-1944), Tomasina Kate Underwood (1887- ), Henry Underwood (1887-1948), Edward Underwood (1888-1957) and Emily Underwood (1891- )