That's an interesting idea and there's no reason why that couldn't work. I do think it might become unwieldy at a certain point or a little unmanageable to apply multiple different income tests or settlement funds tests to different ages of parents. I think also it makes assumptions that younger parents may or may not work. Even if they're able to, they may choose not to. Also, older parents, even though past the retirement age, may choose to work.
On October 27th, 2016. See this statement in context.