My brother has a Medicaid Waiver and caregivers come into the home for 5 to 8 hours a day. My father is unable to assist him for the other times due to mobility issues. My brother could qualify for placement in a wonderful group home/ community but my father refuses to consider it. My brother is 48 yo. He has the mental ability of a 3 yo. I work full time and live an hour away. He has a caregiver who really loves him and does not want him in a home either. She and my father expect my brother to live with me when my father passes. I always thought I could do this, but I am 61 yo and working full time, so I don't think it is feasible. When caregivers are not able to work overnight or during evening hours, I worry about my brother's safety. My father is a narcissistic alcoholic, who no longer drinks. I know I could probably get custody of my brother but I also know it would be a fight because my father wants to continue to get my brother's SSI. I am also worried I won't be able to get him placed in a group home if I get custody and I have no room for him to live with me. I need advice. To get custody also costs around $2,500, which I don't have right now.
Your post makes me very sad, because it's impossible to ignore the thought that if your brother hadn't been so encircled by the family for so many years then maybe his mental age might have risen a bit. Love is love, there is no substitute for it, but it is not enough on its own to realize a person's full potential.
The caregiver who doesn't want him placed when your father passes away: what do she and her co-workers provide for him in the way of enrichment? Do they take him out of the family home?
Looking ahead: I have been glad to read that life expectancy for people with Down Syndrome has risen, and 48 is no longer the advanced age that it would have been twenty or thirty years ago. However, that has meant that the challenges that affect all older age populations are also now more common for them, and that makes your reservations about his living with you permanently all the more valid. It is very likely that he is going to need much more support than you, getting older yourself, will be able to give him.
Don't start a fight with your father, because you have time, and you don't have to be alone in making the best decisions for your brother. Where I'd start is actually with him: if he doesn't already have opportunities for wider socialization, offer them; if nobody is talking to him about what he thinks about the outside world, other people like him, friends, what he likes to do, what makes him happy, then it's time someone did.
Are you in touch with any Down Syndrome support or advocacy groups?
The UK has just enacted legislation to protect the rights of people with Down Syndrome though I blush to admit I haven't read up on it (good intentions...) But I expect its key features will be summarized somewhere, and that you will find reassurance that you are not only being reasonable but also correct in believing that your brother deserves better than you'll be able to give him - and possibly, with all respect to your parents' devotion and hard work, than he's been offered so far.
PS
The Down Syndrome Act 2022 was passed on the 28th April and is now law. *Implementing* is going to be a work in progress! - but that's true of all equality legislation. It all takes time...
Have a look at this page, there's a downloadable booklet at the bottom: https://www.downs-syndrome.org.uk/about-downs-syndrome/health-and-wellbeing/ageing-and-dementia/. I only suggest this as an example - I'm sure there will be local groups in your part of America with more direct relevance for you.
Its time to make plans. The Caregiver will not be responsible once Dad dies. It is so hard to find a group home. To be honest, he should have been placed years ago. He would have had socialization, maybe some schooling and activities. His intelligence may have improved. But that's hindsight. You could get guardianship but that is expensive.