I will send through what I can, when time allows and I'm back in Canberra I'll try and find things out and chase down what I can, although mum's house was recently repossessed by the Govt as part of the asbestosis issue with anything stored in the under house cavity to be destroyed.
I mentioned that mum was sick as I have friend who is adopted with no knowledge of familial health issues to watch out for, everything you've found lines up with my knowledge, I will share that my mother has it would appear at 68 yo early stage Alzheimers or one of the types of dementia, which is something my grandmother Grace suffered from and eventually died from as well. Grace also had breast cancer and a heart attack, she died when I was 8 yo so not much more detail there sorry. Although mum and I both have high cholesterol levels and I've had a minor incident on the heart front too (blockage cleared and stent inserted).
I have a pretty good memory of what mum has mentioned through out her research and then as part of general conversation so I have bashed out as much of it as I can below, I hope it fills in some more blanks for you, sorry but I will interchange Beatrice and Kelly regularly I'm sorry, but its the same person.
The reason for emigrating was the fact Beatrice (Kelly) was unable to survive the English winters she lost a couple of sets of twins, one set before she left England and the second set in Australia before her third surviving child, Colin was born, hence he was 10 years younger than Brenda. Colin passed away in 1998, he had two children from his first marriage one of whom has also passed away, the other I believe is late 60's and worked in the ACT region.
Apparently your grand mother Amanda came out to assist her sister, Beatrice with the raising of the children due to Kelly's ill health, there were apparently 7 kids in that generation, 2 boys lost in WW1 and 5 girls. Beatrice's immediately older sister was Aunty Gertie, so I assume Gertrude.
Mum does refer to her pop, Ernest, as being known as 'Dick', he was the carpenter who built the original stair case and display woodwork in the original Manly Hotel, Pub that sat opposite the ferry terminal.
The Morris side of the family if you go back far enough apparently links back to Lord Nuffield from northern UK around Sheffield with links to Yorkshire. Trivia I know but mum mentioned it regularly, they came down to London when they steamed out to Australia on the train the Flying Scotsman.
I will try to remember more and given mums condition she may remember more as time passes.