I know its been a while since you posted but I have been doing research into my family history and believe that David Andersons mother, Sarah Jane Thompson Anderson, was likely a sister of my great grandmother. David must have married and emigrated at some stage after 1901 as he appears as 'not married' on the 1901 Irish census entry for his father, also David, who was a farmer in the Commons, Newry; and on his marriage registration to Alice Moulton in Vancouver in 1911 he is shown as 'widowed'.
I also know his brother Frederick emigrated to the USA in 1911 on the Caledonia to New York and was going to people called Moore in Detroit.
I may have more information when I view church records and visit PRONI later this year
Hope this is of interest