In a family with five kids, Leonard was the only boy. I don't have married names for his sisters, but their names are: Lois M. (1919), Irma C. (1920), Ellen M. (1923), Iris L. (1927). The years of birth (in parentheses) may be a year off. Leonard was the oldest being born in 1916. Of the five children, all but Ellen and Iris were born in ID (most likely in Payette County) and Ellen and Iris were born in CA (most likely in Siskiyou County).
Leonard's mother was named Mary L. ? (b. abt. 1892 in ID) and his father, Arthur, had two brothers: Hugh H. (1885) and William J. (1889). Hugh was older, William younger. After William, Arthur's parents (Henry B. and Amanda S.) had three daughters: Mabel E. (1892), Gladys F. (1899), and Esther N. (1904). Of the daughters, I only know that Esther married a George O'Leary of Illinois. Hugh married a Viola and has Cecil and Challis (two boys). I don't know if William married.
I'm still researching this line and have not had any direct contact with anyone in it. Best of luck with your search and I hope this helps.