Has anyone had success getting a LO to change their choice of POA and successor trustee?

My MIL is 85, in excellent health and has no memory issues. She was widowed three years ago, and my FIL had handled all their bills and finances (and not all that well either.

One of my brothers-in-law is living with her now, and because it's convenient, she decided to change her trust to make him Successor Trustee and give him POA. Out of seven kids, BIL is probably the second-least qualified to handle this job. (#1 least-qualified was the previous POA and Successor Trustee.)

My BIL is not a bad guy, but he has no idea what he should be doing to help my MIL maintain her estate for her future care and support, and she's in danger of losing everything due to some illegal things my SIL is doing at a rental property my MIL owns. My husband and another brother (there are seven kids in all) are the only two who are best qualified to handle things for her, plus neither are motivated by future inheritances because they don't need her money. The others all do want to inherit, largely because they've never been good at managing their own money. While the two brothers don't need her money, they also can't afford to support her if she needed to go into a nursing home if she had no money of her own.

So, has anyone ever found a way to persuade a competent (for now) parent to make a change to their trust that truly would be in their best interests? As you can imagine, there are far too many cooks in this kitchen, and everyone has an opinion in the family.