Hi
Had a quick look at your family details posted above and hope you find the following few snippets of data useful.
I note a William Joseph Minshaw FORBES on the Queensland electoral rolls from 1903 to 1925. His occupation was butcher. Do you think he may be of yours? The name Minshaw is most unusual.
FORBES William Joseph Minshaw was buried in the Toowong Cemetery on the 19 Apr 1932 Aged 79 years
In the same grave is his wife Martha FORBES who died on 12 Nov 1906 aged 61 years.
Marriage Queensland
1875/C160
FORBES William Joseph Minshaw
BARRETT Martha
There are five births to this couple on
https://www.bdm.qld.gov.au/IndexSearch/BirIndexQry.mYou mention that Christina CAMERON was the wife of Peter William Minshaw FORBES however this marriage reg shows his wife to be Sarah CAMERON and the birth indexes have her as Christina. Perhaps she was Sarah Christina.
1256/1877
FORBES Peter William M
CAMERON Sarah
District Sydney
James Samuel FORBES son of Peter WD and Amelia - you have a death of 1893 however there is this death in NSW
8242/1931
FORBES James S
Father Peter W D Mother Amelia
District Glebe
Another death
22338/1936
SCURR Mary Amelia
Father Peter William D Mother Amelia Reed
District Newtown
This marriage may be Hannah Rachel

429/1878
CAVILL Francis Walter
FORBES Hannah R
District Sydney
Death of a child in 1800 and there is another in 1879 but I detail this one as it is the same year as the death of Ann R CAVILL possibly Hannah R.
Deaths
1837/1880
CAVILL Walter H
Father Francis W Mother Hannah R
District Sydney
1643/1880
CAVILL Ann R
Father Peter Died Surry Hills
District Sydney
and husband's 2nd marriage
699/1883
CAVILL Francis W
MORGAN Elizabeth Jane
District Sydney
Enough for you to sort through
Cheers
Cando