I am not doing the Lahay family but the Ball family. There may be some connection between some of the messages I read here or there may not. I will give you all the information I have on Lahay and hope it helps someone.
Ontario Archives: Marriage of Mary Lahay and Lorenzo Ball, Jan.3,1878.
Mary's age is given as 21, making her born in 1857. Place of birth is given as Glengarry.
St.James Church Records: Marriage of Mary and Lorenzo Jan.31,1878. Mary' age is given as 21, making her born in 1857. Place of birth is given as Glengarry. (Jan.3 or Jan. 31, could be the difficulty in reading some microfilm records)
The 1881 census. Mary's age is given as 23 making her born in 1858. Mary's birth place is given as Quebec.
The 1891 census: Mary's age is given as 36 making her born in 1855. It is also noted that her ancestry is given as French but I do not know if this was from the 1881 or 1891 census. Both archive records and church records list her parents as John and Mary Lahay. The witnessess are John and Rosie Lahay.
We recently have found a Joseph Lahay brother of Mary, who married a Margaret Jane Ball, sister of Mary's husband Lorenzo Ball.
This is all I have, but if you feel you are connected to the Ball/Lahay somehow just leave me a message and we can check it out.