Denise, I can't see a marriage for Jane & Jack Smith in St Mary's records at the moment. I've looked up to 1928. I'll check later records as soon as I get a chance.
Nor can I see a second marriage for Mary A. Cunningham to Creer. Have you tried somewhere like Kirk Braddan for Mary A's marriage?

The following records are from St Mary's R. C. Church Hill St. Douglas
Marriage: 04 June 1881
Patrick Cunningham,3 New Bond St. son of John Cunningham to Mary Ann Clifford, 16 Athol St. dau of Patrick Clifford.
witnesses John Murphy of Pulrose & Mary Ann Cunningham, 3 New Bond St. Douglas

Children of Patrick & Mary Ann Cunningham:

Mary Ellen, born 07 Jan 1884, bapt. 14 Jan 1884 godparents Arthur Cunningham & Ann Rogers

John, born 31 Jan 1886, bapt 07 Feb 1886, godparents Patrick & Jane Watterson
(probably an aunt, as Jane Watterson, nee Clifford)

Patrick, born 31 March 1888, bapt 01 Apr. 1888
(sorry, I didn't copy names of godparents)
Patrick married Helen Louisa Cannell 05 April 1923

Jane, born 12 June 1889, bapt. 29 June 1889
godparent John Watterson

Hope this is of some help. Marie Radcliffe