Hi,
Thank you for your message.
Have you tried looking into their emigration for more information? Generally more information was given at the port of arrival rather than that of departure, so this may be a place to find out more-and maybe even a specific place of origin. For information on immigration records in Canada check the National Library and Archives at http://www.collectionscanada.gc.ca/index-e.html
Another good website is: http://www.irish-genealogy-toolkit.com/Canadian-immigration-records.html
Another possibility is searching the Tithe Applotment Books. These are land records that Books were compiled between 1823 and 1837 in order to determine the amount which occupiers of agricultural holdings should pay in tithes to the Church of Ireland. Although they do not offer any genealogical information they can be used to tie a person to a specific place. I have already done a search of the database but no results were returned. However, I am not familiar with the surname and am unsure of possible variations in spelling. Perhaps you may have more luck. Here is a link to the website where you can search:
http://titheapplotmentbooks.nationalarchives.ie/search/tab/index.jsp
It may be an idea to search the latter land record, Griffith?s Valuation (1848-1864), to see if you can find any Seens that remained in Ireland.
http://www.askaboutireland.ie/griffith-valuation/
You could also try searching at https://familysearch.org/ This is a huge database of genealogical records compiled by the Church of the Latter Day Saints. If you can find a marriage record for John and Mary, or baptismal records for their children, it will give you a place of origin.
Some other websites which you may find useful are:
The National Archives of Ireland http://www.nationalarchives.ie/genealogy1/genealogy-records/introduction/
The National Library of Ireland http://www.nli.ie/en/family-history-introduction.aspx
The National Archives UK ? genealogy search: http://www.nationalarchives.gov.uk/records/looking-for-person/
The Public Records Office of Northern Ireland http://www.proni.gov.uk/index/family_history.htm
Genealogy Links: http://www.genealogylinks.net/uk/ireland/tyrone/index.html
Alternatively, you could contact the Irish World Heritage Centre in Tyrone for assistance, however a fee may apply. Here are their contact details:
Irish World Heritage Centre,
51 Dungannon Road,
Coalisland,
Co. Tyrone B71 4HP
Phone: +44 28 87746065 Email: info@irish-world.com
I hope that this is helpful and that are able to find your ancestors place of origin. Once you do, more avenues of research will open up for you. Best of luck!
Kind regards,
Genealogy Support