Erline and Hershel Pitre are twins born January 2, 1918 in Louisiana to Moise Pitre and Ola Lafleur. In 1920, they were all living in Evangeline Parish, Louisiana. There were three children in the home - Austin, Euline (aka Erline), and Hurshel (aka Hershel). 
Hershel and Erline (EvlineEuline) Pitre appear in both the 1930 and 1940 census with Moise and Ola (Alla) in the same house. 
Auston Pitrie's obituary in 2007 lists only his sister, Patsy, as a surviving sibling so Erline likely died before 2007.
↑ "United States Census, 1940," database with images, FamilySearch Moise Petre, Ville Platte, Police Jury Ward 1, Evangeline, Louisiana, United States citing enumeration district (ED) 20-1, sheet 5A, family 95, Sixteenth Census of the United States, 1940, NARA digital publication T627. Records of the Bureau of the Census, 1790 - 2007, RG 29. Washington, D.C.: National Archives and Records Administration, 2012, roll 1400.
↑ Find A Grave, database and images : accessed 27 July 2019, memorial page for Auston Pitre (23 Dec 1912–13 Sep 2007), Find A Grave: Memorial #21551428, citing Sacred Heart Catholic Church Cemetery, Ville Platte, Evangeline Parish, Louisiana, USA ; Maintained by Rita Graves (contributor 46836288).
"United States Social Security Death Index," database, FamilySearch Hershel Pitre, 08 Dec 1991 citing U.S. Social Security Administration, Death Master File, database (Alexandria, Virginia: National Technical Information Service, ongoing).