William Noonan (1816-1888) was born in Ireland and immigrated to the U.S. about 1848 to Massachusetts. He is shown in the 1850 Census report for Hampden, West Springfield, MA where he is listed with the following family members.
Catherine Noonan (1813-1858) - Wife, born in Ireland
Margaret (1838-1879) Daughter, Born in Ireland
Mary (1841 -?) Daughter, Born in Ireland
Thomas (1844-1901) Son, Born in Ireland
Martin (1848-?) Son, Born in Massachusetts
Stephen (1851-1926) Son, Born in Massachusuttes
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They next show up on the 1860 Census in Owosso, Michigan
Only William, Thomas, Martin and Stephen are listed. Catherine passed away after arriving to Michigan in 1858.
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At some point between 1860 and 1870, William remarried Ellen Carmody in Owosso and had two children, William (1868-1913) and Ellen "Ella" (1869-1910). Stephen married Delia M. Davis (1842-1935), Martin married Hattie A. Currier (1856- ?) and Thomas married Mary S. Allen (1845-1917). Margaret married Searl “Cyril” Drown (1827-1920).
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Around 1880 William his wife Ellen, Stephen and Ella all changed their surnames from Noonan to Nonon. This is what is on all of their grave stones. Thomas kept the Noonan spelling, this is my Great Great Grandfather.
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QUESTIONS:
1. Who were William's Parents?
2. Where in Ireland is William from?
3. When did William and Catherine get married, and what is her maiden name?
4. When did they arrive in the U.S. and on which ship?
5. Where did Mary go? I cannot locate her in Michigan with the family..
6. Why did they change their name from Noonan to Nonon.

Any information would be extremely grateful.

Thank You