Karen- I don't have the answer you are looking for, but may have some information that will help you. It should at least give you a place in Quebec to begin the search.
There were several Fecteau/Fecto families in Detroit in the 1870 census. I found one family, Michael, age 59, Catherine, age 40, Felix, age 20, Delima, age 18, and 7 younger children. Only the 2 year old was born in Michigan.
I am quite certain this is actually Magloire Fecteau and Catherine Dompierre. I know that Magloire Fecteau, son of Thomas Fecteau and Marguerite Jacques married Catherine Dompierre on 11 Nov. 1845 at Ste. Marie, Beauce, Quebec. I know that they had Catherine, born 1846, Marie Adelaide, born 1848, Felix, born 1850 and Delima, born 1853. Magloire was a blacksmith in Quebec, but Michael was simply listed as a laborer. I also know that none of Magloire's children married in Beauce, because they are not listed in the marriage repertoire for Beauce, Dorchester and Frontenac.
Another family in the 1870 Detroit census is Thomas Fecto, 54,Rosa, 50, Fred,25, Joseph, 15, Crawford, 11, Elisabeth, 8. I suspect that this is Thomas Fecteau, son of Thomas Fecteau and Marguerite Jacques, who was born in 1817 and married in 1837 in Ste. Marie, Beauce. Magloire and Thomas were brothers.
Several of Magloire/Michael's siblings ended up in Michigan, too. My direct ancestor, Marguerite Fecteau married Francois Turmell and settled in Bay City, MI about 1880. Another sister, Julie Fecteau married Jean Turmel and also settled in Bay City, Michigan.
I would suggest that you look for this family in the Beauce area of Quebec, specifically Ste. Marie, Beauce.
Let me know if I can help you with any more details.