Your parents have over 1MM plus a big pension.
They need in home assistance, they need to hire someone to come in daily to help out, attend to things, etc.
Possibly they do need night time supervision, but start with the day only as a much easier step.
This will cost about $30K to 60K per year, but their pension can easily cover it.
Your DS does not have to quit her job (DS is not prepared to be a care-giver) and its quite likely you both will still be splitting a 1 MM inheritance.
Make sure both of you get on as co-signer to parents accounts, and review accounts (online?) every couple of months.
You don't want a care-giver to steal it all, and you will probably go through 1 or 2 care-givers per year as its a tough job. (which is why DS cannot do it).
I realize they're 'wanting their cake and to eat it too,' but they can't stand the idea of having strangers in their house, or sister and I when we're not needed frankly (hence they want her to move nearby, but have her own apartment even though they have two spare bedrooms). They hired people to handle the pool and yard, and they have a paid handyman they've known for years who helps out as needed.
Inside the house is a different matter, it's their "nest." They have a maid once/week, but Mom has never gotten comfortable with the idea, she absolutely hates it. How we would get them to accept more help than a maid is beyond sister and I. I am afraid it's going to take a serious injury for either of them to even consider it, and I suspect they will still do everything they can to avoid "outsider" help.
Sister is willing to be their outside help, but she realizes as the months/years pass there may well be things she can't do for them.
They simply won't talk about independent living/assisted living/nursing care. They'd literally get up and walk away if we tried to force that conversation.
I know the advice we've gotten here is correct, but not how to get from point A to point B without a catastrophe in the meantime. They're determined to die peacefully in their sleep, without anyone's help, except sister.
Thanks again. Sister and I have been comparing notes for years, and we've exchanged thoughts extensively in the past two days. And we've both gently confronted Dad last night. We'll see where it leads.