... i will follow all this up and keep looking for more ...
Then here are another couple of potential siblings of John to follow up on, in case you haven't run into them yet. Both of the following marriages took place in Mullavilly Church of Ireland, which was where John Laurinson married Sarah Jane Gibson in 1875.
(1) Christmas Eve in 1866, Elizabeth Laurison of Ballylisk married William John Finn, the bride's father was recorded as William Laurison, Pensioner:
https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_returns/marriages_1866/11548/8247968.pdfIf you look at the relevant previous post showing the location of Mullavilly townland, you can see that Ballylisk borders it. 'Pensioner' is what John Laurinson's father William was recorded as when John married Sarah Jane Gibson in 1875. BTW, you'll find at least a couple of Finn children to William John and Elizabeth.
(2) New year's day in 1872, Wilson Laurison of 'Cornascribe' married Elizabeth Jeffers, the groom's father was recorded as William Laurison, Labourer:
https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_returns/marriages_1872/11292/8142778.pdf'Cornascribe' (Cornascreeb) was where John Laurinson said he was living when he married Sarah Jane Gibson in 1875 and is close to Mullavilly / Ballylisk. You'll also find children to Wilson and Elizabeth.
I wonder if Elizabeth Jeffers could be the daughter-in-law informant of the following death for a 71 year old widow Elizabeth Laurison who died at Cornascreeb in February 1889:
https://civilrecords.irishgenealogy.ie/churchrecords/images/deaths_returns/deaths_1889/06154/4758343.pdfI also wonder about the following entry in the Diocesan and Prerogative Marriage Licence Bonds Indexes, 1623 - 1866, it's an 1841 marriage in the Diocese of Armagh between a William Laurison and Elizabeth Flavell / Wilson, it doesn't work with John's estimated birth year, unless he was pre-marriage or from a previous marriage, but still, just to note for now until it can be ruled out:
http://census.nationalarchives.ie/reels/dm/IRE_DIOC_007246526_00535.pdf