Thank you for your message.
Have you tried looking in church records for information on the family? Do you know their religious denomination?
Most Catholic records are held locally, however you can see what records are available in each parish on the irishtimes website. For Lettermacward/Dungloe follow this link:
Do you know much about their emigration? Generally more information was given at the port of arrival rather than that of departure so it may be a place to find information. Here is a link to the Canadian National Library and Archives where you can find more information on this:
Depending on when he returned, you may be able to find record of James in the 1901 census records. You can check these online here: http://www.census.nationalarchives.ie/search/
Depending on when they emigrated you may find record of the family in the land records. There are two:
The Tithe Applotment Books (1823-1838) found at http://titheapplotmentbooks.nationalarchives.ie/search/tab/home.jsp
and Griffith's Valuation (1848-1864) found at http://www.askaboutireland.ie/griffith-valuation/
Some other websites which may be helpful 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
Family Search: https://familysearch.org/
Genealogy Links: http://www.genealogylinks.net/uk/ireland/donegal/index.html
You could also try contacting the Donegal Ancestry Centre for assistance. However, a fee may apply. Here are their contact details:
Donegal Ancestry Centre,
Phone: +353 (0) 74 9151266 Email: email@example.com
I hope that this is helpful. Remember to post as much information as you can with regard to the people you are researching. The more information you post, the more likely it is that one of our volunteers will be able to advise or assist you. Also include information concerning which sources you may have already used so others may further your search.