Looking for Information and Connections

Looking for any information regarding a John J. Sullivan (b. abt 1846) and his wife Margaret O'Brien (b. abt 1850.  John J. immigrated to the U.S. and fought  in the Civil War as a member of the Union Army.  Returned to Ireland and possibly married there.  First Child Mary,  (b. 9 Sept 1864 in Kildorrery). Second child Dennis (b. 5 April 1867 in Kildorrery), Third Child Johanna (b. 10 June 1869 in Kildorrery and Patrick J. (b. 5 Sept 1863 possibly in Kildorrery) all 4 children named above immigrated to the U.S.A., Boston, Mass.  Would like to have any further information that might be available regarding the history and descendants of the above.  Thank you.  Brian Sullivan