Only thing I'm wondering - They have James recorded as 4 years old on the 1911 census when we know that he was born 1883
James b. 1883 is with his wife and family nearby in Ballyhowne, that 4 year old must be another James, I haven't looked into him, but perhaps Joseph's son.
Edited to add: I also wouldn't be surprised if it was a double entry in the census for the son James born to James Mullan and Margaret Dowie, the families were living near each other, maybe 4 year old James was visiting the grandparents. It looks like the Joseph Mullan listed as married in that 1911 census return was married to Susanna Patterson in 1906, I can see possible children to the couple, but no James to match the 4 year old in the census return:
https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_returns/marriages_1906/10123/5683040.pdfBTW, I should have said by now, the Jane Mullan in grave E1 254, City Cemetery - Glenalina Extension (reply #5) may well be Jemima's sister Jane, the one born in Scotland. The age in the burial record is in the ballpark and I haven't yet found a marriage record for her.