Very interesting woman. I've been studying Irish immigration in the lead mining region of Illinois/Wisconsin and would love to learn more about if you have more to share.
Hope this input doesn't confuse anything, but I found a few interesting sources that reference her. If accurate, Margaret had at least one little sister and at least two brothers, who emigrated to Australia. Possibly more...
The 1860 census, Galena, IL, enumerates in the house of Dennis and Margaret Branan a girl named Rose Branan, 16 years old, born in Ireland, listed as sister-in-law. So perhaps Margaret had a little sister come live with her? See: https://www.familysearch.org/ark:/61903/3:1:33S7-9YB6-9B44?i=8&cc=14731…
In "The Illustrated History of Nebraska" Vol. III (1913), it profiles Dennis James Flaherty, son of Dennis and Margaret. It says: "FLAHERTY, DENIS JAMES, attorney at law, Lincoln, Neb., was born at Galena, Ill., February, 1875, son of Denis O. Flaherty, who was born in County Donegal, Ireland, February 12, 1834, and came to America in 1855. In 1856 he was married to Margaret Brennan, at Benton, Wis., who was also a native of County Donegal, Ireland, born in 1836. Mrs. Flaherty was the daughter of William Brennan, who served under Wellington in the wars against Napoleon I. Two of her brothers, Michael and James, have held office for many years under the British government of Australia, where they located in 1850. Her death occurred October 9, 1909. Denis O. Flaherty engaged in the milling business at Galena, Ill., until 1865, when he went to Idaho, and took up a placer claim near Boise, which he worked for two years, then returned to Illinois and engaged in farming near Galena until 1877, when he moved to Cedar county, Ned., and engaged in farming and stock-raising. He served as county commissioner of Cedar county three terms. His death occurred February 12, 1896." The article goes on another paragraph or so listing their children with respective biographical information. See: https://books.google.com/books?id=-WJKAAAAYAAJ&printsec=frontcover#v=on…
On 27 July 1856, a man named Michael Flaherty married Catherine Brenan in Jo Daviess County, IL. Galena, where Margaret is living at this time, is the capital of Jo Daviess County. It seems likely that Catherine is a relation of Margaret.
