At bandmate Natalie Maines` sister Kim`s wedding Martie met Gareth Maguire, a Roman Catholic teacher and actor from Northern Ireland. The couple became engaged in June, 2001, and married August 10, 2001, in a civil ceremony in Hawaii. Later they had a Catholic "blessing" ceremony in the groom`s hometown, Carnlough in County Antrim, Ireland, on March 9, 2002, for all the guests that were not able to attend the first wedding. She said of the ceremony that the Catholic Church would not permit a wedding service due to her prior divorce. Maguire says ruefully that there were so many "special" people that they`d wanted to include, but that they just couldn`t wait to marry. Part of the reason for the rush was Gareth`s need to keep flying back and forth because of visa considerations.
After her marriage, Martie changed her name to that of her new husband, which is why in her musical career she has had the surnames of Erwin, Seidel, and now, Maguire.
Twin girls, with Gareth, born 27 April 2004. Eva Ruth Maguire, 5 lbs, 13 oz, and Kathleen Emilie Maguire, 6 lbs, 1 oz. third child Harper Rosie Maguire, on Friday in Austin, Texas on July 25, 2008 The baby, who weighed 7 lb., 10 oz. and was 20.5 inches long.