I came across a treeholder jennifer who has a John Boyce b1815 Ballydongan, Down on Genes Reunited which I think you have to join to ask permission of the treeholder to see their tree. However I did asearch for mary jane McCormick with different spellings but found no match, so David hoping this is not you in disguise
Joans Griffiths list led me
http://www.askaboutireland.ie/griffith-valuation/ to look for more details
looking at John Boyce in Griffiths there are 6 entries for John Boyce in Ballydugan, Tullylish here they are by map reference
1 map ref 51 his is 51b , a David Boyce has 51a, whose name is on both ie he is older than John , 52a is William Boyce and he leases 52 b
2 map ref 75a John Boyce b is James Boyce John is the older
3 James at map ref 75 a sub lease?
4 John Boyce map ref 77
5 map ref 79 John Boyce has 7 acres and house v £3 ten shillingspa the highest value on the page except forWm Boyce at 78 a at £4pa
6 ballynagarrick upper map ref 21
I dint look up the map supplied, but that is fun then you can alter the image to current pick up the nearest roads, stop go to moderngoogle find thet road and rough spot of where relatives livedm magnify go into satellite magnify click on the orad most likely spot and then asee street scenes along the bottom of your screen I normally click on the first one and then by clicking the image of the road scene real of a couple of years ago, go up and down the road looking left and right and just sometimes the older buildings could be where you family lived, or be the site of the demolished blg etc
my assumptions there appears to be as many Boyce in the townland as there are Dines who are much bigger and wealthier, so a younger son might feel no future for him, I also imagine there are two john boyce a father and son, and another possibly. There might be too many Boyce fin the community and hence John migrates. Or as in my family history I found I could trace relatives revisingting where they had come from ie Wigtownshire, so that’s another avenue.
familysearch.org produced what Joan found so could it be the folklore getting it wrong etc. I woild want o quiz Jennifer above before jumping to conclusions
ie the Hugh Boyce rather than John
so that’s all I can offer, good luck