1997 Boston Globe (formerly provided by Sharon Sergeant/Boston States List) DeCoste - of Jamaica Plain in her 98th year. July 20. Mary Lillian (PETTIPAS), Beloved wife of the late Frank X. DeCoste. Loving mother of Deacon Leonard F. DeCoste of So. Natick and Sister Francis Marilyn, C.S. J. of St. John's School, Canton. Dear sister of Joseph R. Pettipas of Nova Scotia. Dear grandmother of Patricia J. Casalinova, Marilyn Fields both of Natick and the late Michael L. DeCoste. Great grandmother of 6. Also survived by several nieces and nephews.