I would treat all of my children the same.
To do otherwise is making an arbitrary decision based on my perception of them, which may not be the same as the reality they live in.
I have always tried hard to be equal with all my children, and would never be so crass as to indicate that I 'value' one over another in terms of the support i would offer them - monetary or otherwise.
As with most families, their financial circumstances differr, and aalthough once could be perceived as not 'needing' money as much as the others, who I am to make that decision for her? She has children, she can pass it on to them or give to a cats home, it is not my decision how she spends her money, any more than i would make a decision based on her perceived 'worthiness' in my eyes to receive mor or less than her sisters.
For someone to start making decision like that is to continue a distancing from their children that they have already started where it matters - with their parental love, they are simply extending into cold hard cash.