Alright, alright GP, I have a few confessions....... I'm actually not a Dermatologist or a Rhodes Scholar @Bunniekins I was pulling your leg a little bit.........
........I'm a Veterinarian Pathologist who diagnoses Kitty Cancer every day............Ok, Ok, OK, maybe I'm not a Veterinarian Pathologist either 
......I am a 'manager' though, I manage myself pretty well and I guess you could say I am a small business person too because I run this, here homestead 
I think that securing housing for your son is a great idea. It sounds like your eldest boy is well and truly settled on the other side of the world and that he isn't able to check in on him regularly as another support person into the future.
But I think that it is wise to put these measures in as soon as the funds become available because you never know what health or medical obstacles yourself or your ex husband may find yourself in and you won't be capable of helping him forever. None of us are getting any younger Peas. And as you know Pea, MH can change so rapidly, mine most definitely has over the years. Do all the legals and maybe get some advice on how to set it up as a trust to ensure that he always has secure housing. If your other children are upset about the imbalance of what he receives maybe he could write his will that it is inherited by their children if they have any.....I would just definitely get it in place while you and your ex husband are compos mentis.....it's sad that your ex is showing signs of health deterioration. But I suppose he must look at his children and think, well, I got 20/30/40 more years of health compared to them. I think that dementia scares a lot of people, I freak out occasionally but I worry I will get Parkinson's Disease which is on both sides of my family. I have little bursts of anxiety every now and then, but I am hoping that it passes me.
I think that staying in Sydney is what I would do. I don't have any family that lives in regional Australia but I still have friends around there and there just aren't the services or opportunities for people with disabilities. I love big wide open spaces and do get stir crazy here at times, but I know that after all the suffering in childhood that if you don't have good health it is best to stay in the big smoke. I can visit the beach and bush. I think regional Oz would be fine if you had a loving partner, a group of friends and secure employment and housing and not very many health problems. If you don' have many health problems and don't need to see specialists regularly you'd have a ball. And to be honest I have found people in Sydney much more friendly. If you move to smaller cities they are very clicky, people never leave and it is hard to break into their tight little clicks. I guess most people are coupled so they have no interest in being social or friendly because they just need the one person.
What sort of level of health is your mother in Peas? Is she becoming frail?
Corny 