Filed my mother's return as MFS - I filed my father's return also as MFS and that someone could claim him as a dependent.  I am claiming my father as they lived with me and provided more than half of his support.  When I filed the returns mine was "rejected" by the IRS since his SS number appeared on a return that was already filed.  Not sure how to rectify - not sure what I would change - "checked" all the right boxes...thanks