[dragonwriter]

> Your wife can mandate health care when you are otherwise incapable. You have 7 wives. Who has final say.

Establishing a rule for priority in this situation is fairly straightforward. The most obvious rule is to support a pre-need declaration of priority if one exists, and otherwise default to an oldest-marriage priority.

> You get a divorce from one wife. What does she get?

This is essentially an identical issue to dissolution of a partnership with more than two partners, and as such is pretty well already solved by the legal system.