Stephen E.Onderko;78;of Bradenton;Fla.;formerly of Belle Vernon;died Monday;June 7;1999;at 5:10 p.m. at the home of his son in Apollo Beach;Fla. He was born Sept.23;1920;in Monessen;a son of the late John and Mary Zevok Onderko. Mr.Onderko resided in Florida the past seven years and previously lived in Belle Vernon;where he was a former member of St.Sebastian Roman Catholic Church. He retired as a machine operator from the Allenport plant of Wheeling-Pittsburgh Steel Corp. Mr.Onderko was a World War II veteran serving in the U.S.Army. He was a member of the VFW Post in Ruskin;Fla. Survivors include a daughter;Mrs.Allen (Andrea) Barnes of Venetia;two sons and a daughter-in-law;Mark Onderko of Austin;Texas;and Dr.Greg and Denise Onderko of Apollo Beach;Fla.;three grandchildren;Christopher Barnes;Zachary Barnes and Noah Onderko;and two brothers;Andrew Onderko of Monessen and Leonard Andrews of Uniontown. In addition to his parents;he was preceded in death by his wife;Julia Urchick Onderko;in July of 1971;and a sister;Martha Bethem. Friends will be received Thursday from 2 to 4 and 7 to 9 p.m. at the Leonard J.Parzynski Funeral home;626 Broad Ave.;Belle Vernon. Prayer service will be held Friday at 9:30 a.m. in the funeral home;followed by Mass at 10 a.m. in St.Sebastian Roman Catholic Church;Belle Vernon;with the Rev.Donald P.Trexler;parochial vicar;as celebrant. Interment will follow in Belle Vernon cemetery. The Legion of Mary will recite the Rosary Thursday at 3 p.m. in the funeral home. Memorial contributions may be made to the Life Path Hospice;1647 Sun City Center Plaza;No.104;Sun City Center;Fla.33573. The Leonard J.Parzynski Funeral Home is in charge of arrangements.