You're right Merlin, the d c does give the name KNABB. Part of the affidavit for administration makes the statement that the name is KNAPP incorrectly spelt as KNABB on the death cert.
None of which helps us find his immigration records; so what I am trying to do is to work out which was the first child born in Australia to help with an immigration record
Random thoughts........
NSW BMD has birth registrations for Caroline Elizabeth and John George - both with parents William and Mary A
V18443407 28/1844 John G KNAPP
V18443406 28/1844 Caroline E KNAPP
Comment - were these twins or are these baptism registrations? (Help, JM!!)
TROVE shows a sad end for Caroline Elizabeth DOIG - burnt in a house fire in January 1913, aged 78, which would give a birthdate of abt 1844.
http://trove.nla.gov.au/ndp/del/article/10762977According to IGI Caroline Elizabeth KNAPP was baptised in 1844 in Melbourne, but this may not be her birth year.
31 December 1844 at St James, Melbourne, New South Wales, Australia
Caroline Elizabeth KNAPP
Parents: William Knapp, Mary Ann
Indexing Project (Batch) Number: C13545-2, GS Film number: 993955
However the age of Caroline Elizabeth from the death certificates (see below) give a birthdate of about 1840/1841 which would seem more logical for a couple married in 1839. And perhaps there was an older John deceased
The children listed on the death certificates are (shown with age at Dec 1856 first then age at Apr 1865), other details have been added form the affidavit of John George KNAPP in 1878 - all were living in Hamilton in 1878 except as listed.
John 18 - no age given on Mary Ann's d c, and he is listed after Elizabeth on that certificate.
Elizabeth 16, 14 - marries Alexander DOIG
George 13, 12 - named as John George on the PROV probate papers
Thomas 12, 10 - living in Edenhope 1878
Amelia 10, 8
Jonathan 8, 6 - living in Sale 1878
Jane 6, 5
Harriet 3, 1.5 - marries George PANOWITZ
It isn't clear from these certificates whether the first child was actually John - was he actually the John George who gained administration of William's estate??
Anyhow, it seems certain that William KNAPP arrived in Australia some time after his marriage in September 1839 and the registration of his children's birth/baptism in 1844.
Sorry have probably just given information already known.
Judith