I agree. One of the first things that I surmised was sibling and in-law marriages ala royalist societies to sew up legacies, inheritances, rights and properties. that includes step-children of age (Woody Allen Wooly handcuffs), scions marrying grandfolks, aunts, uncles. Exes marrying Exes' grandchildren to get back in the lineage. With 50% divorce rates, that's a lot of unrelated former relatives with complementary interests in search of renewed or strengthened standing at the probate hearings. Do five co-married exes and offspring have legal weight comparable to one late-in-life spouse?
And really, if a dog can inherit a family trust, can a full grown goldfish garner power of attorney for an opinionated and vocal 11-year old with proper legal counsel? With a wide enough scope of betrothals, I can be kept in spousal privilege spare kidneys to start my own personality sect. Imagine the marriage laws that aging immortal white men could write.