This is where I got the details of the other two children:
Biographical Index of South Australians 1836-1885
d: 10.5.1881 Semaphore SA
arr: 1853 GOMELZA
0cc: Insurance Company Director
res: Norwood, Semaphore ccl: Cong
ch: Harriett Ellen BRUCE (1841-1891), Maria Groom ANTHONY (1843-1865),
Henry Hutchinson (1847-1897), Annie Eliz (1849-1891), Alfred Wm (1856-), Ruth Marion (1859-)
The family arrived in 1853. Perhaps not born in SA then.
William H C LOVELY b. 13 Jun 1872 c. 8 Aug 1872 Christ Church, North Adelaide, SA
Found one more bit:
Marriages Mar 1840
COWIE Henry Sunderland 24 229
HUTCHINSON Ruth Sunderland 24 229
Liverpool Mercury etc (Liverpool, England), Friday, April 10, 1840; Issue 1447.
On Tuesday, the 31st ult., at Bethel Chapel, Villiers-street, Bishopwearmouth, Sunderland, Mr. Henry Cowie, of this town, to Miss Ruth Hutchinson, of Bishopwearmouth.