Celebrity Parents Mary McCormack Welcomes a Daughter Lillian is the third child for the star of In Plain Sight By People Staff Updated on December 1, 2020 11:10 PM Share Tweet Pin Email Photo: Craig Barritt/WireImage This U.S. marshal now has her own posse. Mary McCormack, who hunts down witnesses on In Plain Sight, delivered her third daughter, Lillian, on Saturday morning, Sept. 10, her rep confirms to PEOPLE. Lillian weighed in at 6 lbs., 15 oz. and is 20 inches long. The actress, 42, and husband Michael Morris s new arrival joins big sisters Rose, 4, and Margaret, 7. McCormack – who gave PEOPLE a tour of her trailer on-set – had her pregnancy written into the storyline of her character Marshal Mary Shannon. – Julie Jordan PHOTOS: Who’s Due Next?