If they're going to provide the value of independence and objectivity, the family needs to know them so they can trust them to do that.

For the ones that are ready for it, that means they're pretty clear on the goals they have for their business and the goals they have for the family.

They'll see it as too much bureaucracy at that stage of their career.

You have to go into the job description before you start hiring. There's a tendency that people worry about 'who' rather than 'what' too quickly.