Kay - I am doing research for a friend, which may intersect with your Hussey line in Roscommon.
Thomas Hussey b abt 1800 married Mary Morgan b abt 1800. They had three children: John Hussey b 1831-32 (m. Mary Curley), Mary Hussey b 1844 (emig to NYC, m. John Cunniff), and Thomas Hussey (b abt 1850, m. Bridget). I believe I've found Thomas and Bridget in the 1901 and 1911 Irish Census in Castlequarter (Kiltullagh, Roscommon).
My friend's direct line descends from John Hussey/Mary Curley's daughter, Bridget Delia b 6-Feb-1872, who married James Thomas Murphy.