From the Drouin Collection at Ancestry:
Québec (Notre-Dame) (Catholic)
Nicholas Myler, son of James Myler and Bridget Roach married Elizabeth Keogh, daughter of Henry Keogh and Elizabeth Dodd on 24 Jun 1851
The entry is written in French and, unfortunately, my French isn't that great so I can't translate the entire entry.
Are they the Nicholas and Elizabeth Meylor in Willow Springs, Lafayette County, Wisconsin on the 1860 US census? If so, border crossing documents weren't kept from that time period as the border between Canada and the US was pretty open then.
There was a Nicholas Myler, 26, workman who arrived on the Boreas in New York on 9 May 1849. There were four others with the surname Myler listed two lines after Nicholas. Their names (in the order they appear on the passenger list) were Catherine (24, spinster), Nancy (29, spinster), Bridget (20, spinster) and Judith (22, spinster). The name on the line between Nicholas and Catherine was Michael Howlan.
There was an Eliza Keogh who was travelling with her parents and siblings on the Roscius which arrived in New York on 18 Sep 1850. Here’s the information from their entry:
Mr. Keogh, 36, male, labourer, the country from which they severly belong: Ireland, the country they intend to be inhabitants: USA, died on board
Mrs. Keogh, 33, female, Ireland, USA
Eliza Keogh, 16, female, Ireland, USA
Con Keogh, 15, male, Ireland, USA
Caroline Keogh, 14, female, Ireland, USA
Frs* Keogh, 12, male, Ireland, USA
*I assume that is an abbreviation for Francis.
Jacquie
Note: fixed my typo on marriage date