This may help you in determining the date of arrival in Canada of the 3 Whitten brothers. This is the marriage notice for Robert Whitten who got married in what was then York (Toronto). It was at St. James Cathedral, because I have some other data (not in hand) that shows this.
15 March, 1844, by license, Robert WHITTEN, of the township of York, bachelor, and Elizabeth FERGUSON, of the same place, spinster.
Anxiously awaiting information on place of origin of Whitten family in Armagh.