FRANCES “SISSY” (GALLAGHER) DUFF – of Billerica formerly of Somerville and Woburn. February 12th at seventy years of age. Daughter of the late Bernard and Gertrude Gallagher. Beloved mother of John Tivnan of Lynn, David Duff, his wife Kristina of Winthrop. Dear sister of Robert Gallagher, his wife Lucille of FL, the late John ‘Jacky’ and Charles Gallagher. Cherished grandmother of Marisa, Maranda, Hannah, Jaxon, Nicholas, Dillon and also their mother Carol Hancock of Somerville. Also survived by many nieces, nephews, and cousins. A Memorial Service will be held in the Chapel at Woodlawn Cemetery, Everett, Saturday, June 3rd at 10 a.m. followed by interment.