Rainier's grandfather didn't need to pull strings for him to be included. Those strings were pulled for his mother, Charlotte, who was born out of wedlock but who was legitimated, adopted, and declared heir four or five years before Rainier was born. Charlotte later ceded her rights to the Princely Seat in favor of Rainier.

All of that is straightforward in comparison to the new laws in Japan. I can't wrap my head around how those will work in practice.