Jacqui, I have come across a few things which may add a bit to your confusion.
Birth:
John Ruxton Weir
born:20 July 1882 baptised:24 July 1882 at St Mary's Pro-Cathedral
address:51 Jervis St,Dublin
parents:William Weir and Sarah Ruxton
sponsors:Catherine Byrne/Charles Maher
*here's the problem;Sarah Ruxton was John's mother. Its highly unlikely he married her and had children with her.
Marriage:
date of marriage:29 June 1881
place of marriage: St Mary's Pro Cathedral (COI) Dublin
groom:William Weir
groom's address:51 Jervis St,Dublin
groom's occ:commercial clerk
groom's father:Robert Weir-farmer
bride:Sarah Charlton
bride's address:51 Jervis St,Dublin
bride's father: John Ruxton-commercial clerk
witnesses:John O'Dawd(hus)/Jane Ruxton(wife)
Marriage:
date of marriage:18 Aug 1862
place of marriage:St Mary's Pro Cathedral,Dublin
bride:Sarah Ruxton
bride's father:John Ruxton
groom:James Charleton
groom's father:John Charleton
groom's occ:house painter
bride's occ:waistcoat maker
witnesses:William Ruxton(hus)/Jane Ruxton(wife)
Sarah Ruxton died 5 May 1909 in Dublin born @ 1845
Kathleen Kiely and John Weir were married Jan-March 1908 Dublin North
1901 Irish census;
Cashel,Kiledmond,Carlow
Patrick Kealy age 20, head of house,roman catholic,born Carlow,farmer,single
Katie Kealy age 24,sister,roman catholic,born Carlow,single
Ellie Kealy age 24,sister,roman catholic,born Carlow,single
Maria Kealy age 22,roman catholic,born Carlow,single
1901 Irish census;
Rutland Square,Rotunda(which is a hospital in Dublin),Dublin
William Weir age 58,head of house,church of Ireland,born co Sligo,occ:apothecary,married
Sarah Weir age 45,wife,roman catholic,born co Dublin,occ:boarding house proprietress,married
Della Weir age 3,niece,church of Ireland,born co Dublin,scholar,single
John Weir age 18,son,roman catholic,born Dublin,occ:dentists apprentice,single
Jane Ruxton age 33,wife's sister,roman catholic,born Dublin,single
Rose Ruxton age 28,wife's sister,roman catholic,born Dublin,single
Incoming passengers to UK:
John Weir age 29, born @ 1880, 2nd class,departed:NY,arriving at Liverpool and Queenstown,10 April 1909,ship:Lusitania
Catherine Weir age 35,born@ 1874,1st class,departed:NY,arriving at Liverpool and Queenstown,2 November 1909,ship:Lusitania
*reason may be the illness of John's father William
Probate:
William Ormsby Weir
will probated 25 April 1910
died:4 March 1910 Dublin
beneficiary:John R Weir
Administration of the estate of William Ormsby Weir,late of 10 Nelson Street Dublin,medical doctor,who died 4 March 1910,granted at Dublin to John R Weir esquire,effects £280. 1s 2d.
I think I have discovered part of the story " Sarah threw John out".I don't think it was Sarah,I think it was Kathleen.
Valuation rolls 1920 Glasgow:
Kate Weir has a house and loomshop at 33 Lockhart St,Stonehouse,co Lanarkshire
John Weir has a house at 18 Howat Street,Govan,Glasgow,co Lanarkshire
Look all this over and tell me what you think.I believe that John was always married to Kathleen/Catherine and that it was she who probably threw him out.If you can give me names of children I will check census. I do not see how John could have married Sarah as her age,if she was alive,would have prohibited her from having children.Hope this helps,Kim