1871 BELLEVILLE, HASTINGS WEST, ONTARIO
David, age 29, grocer, born ON
Eliza, age 20, born ON
Emily, age 3,born ON
You asked for info between 1840 and 1870 so I am assuming you know David and Eliza moved to Michigan by 1880 - at least I believe it is the same couple - they have three children Charles E. 7, Emily, 4, and Peter S., 2 - eldest daughter Emily may have died
David and Eliza both born Canada
There are also some marriages at familysearch.org for children of Dsvid Cox and Eliza McSherry - Michigan marriages
1861 HASTINGS, CANADA WEST
Philip, age 59, farmer, born England
May, age 58, born England
David, age 19, born England
Maria, age 13, born England
Daniel, age 9, born England
James, age 24, born Upper Canada
Eliza, age 21, born Ireland
Charles, age 2, born Upper Canada
Hugh, age 1, born Upper Çanada
So in this one David is shown born England but in other census he is shown born Canada
1861 SIDNEY, HASTINGS, CANADA WEST
Eliza J., age 15, born Canada
she seems to be alone, under females in family it shows one, males none are shown.Three pages later I found Peter McSherry, age 45, born Ireland, and Mary McSherry, age 60, born Lower Canada - so now sure how they fit but wanted to give you the info - Peter, could, I suppose be Eliza/s father but then who is Mary?
Also, this Eliza is 15 in 1861 but in 1871 your Eliza is 20 - census are often out but seems like a lot for a young woman.
I tried to find Peter and Eliza in 1851 to see what children were with them, but no luck yet.
I did find a death fora Peter McSherry who died in 1920 at age 77. Parents shown as Peter McSherry - born Ireland and Liza Jane Hill- born Scotland.
This Peter shown as born Stubin County, New York
so from age he was born about 1843 in NY
But I see him in census shown as born Canada
I cannot find the McSherry family in 1851/52 Canada census
I do see that there is a Peter McSherry , born Ireland who is in 1880 US Federal census mortality schedule - he died age 69 - March 1880, Ostego, MI
on same page is a Maria E. Cox, age 11, born Canada, died Oct. 1879 Ostego, MI
I wonder if Marie E., could be a child of David and Eliza ? Ostego Co. is where I found the David and Eliza I mentioned above in 1880.
Sorry I couldn't find more.