Frederick married Clara M. Stumbillig on 17 May 1899 in Pittsburgh, Allegheny County, Pennsylvania, USA. Clara (daughter of Joseph Stumbillig and Barbara Lauth) was born on 10 Jul 1872 in Pittsburgh, Allegheny County, Pennsylvania, USA; died on 11 Feb 1960 in Green Tree, Allegheny County, Pennsylvania, USA; was buried on 14 Feb 1960 in Saint Martin's Cemetery, Pittsburgh, Allegheny County, Pennsylvania, USA. [Group Sheet] [Family Chart]

1. Barbara Ann Cornelius was born in 0Apr 1900 in Allegheny County, Pennsylvania, USA; died in 1970; was buried in Saint Martin's Cemetery, Pittsburgh, Allegheny County, Pennsylvania, USA.
2. Frederick Joseph Cornelius was born on 23 Sep 1904 in Pittsburgh, Allegheny County, Pennsylvania, USA; died on 8 May 1976 in Pittsburgh, Allegheny County, Pennsylvania, USA; was buried in Resurrection Cemetery, Moon Township, Allegheny County, Pennsylvania, USA.
3. Francis Joseph Cornelius was born on 12 Jul 1908 in Pittsburgh, Allegheny County, Pennsylvania, USA; died on 10 Aug 1981 in Pittsburgh, Allegheny County, Pennsylvania, USA; was buried in Resurrection Cemetery, Moon Township, Allegheny County, Pennsylvania, USA.