I once charted a family in a remote island where the “first cousin” line was marked with a blue dot, and the next generation had a special feather ritual to show that the taboo was broken in a sacred way. Try drawing a simple line for each generation and put a little symbol (maybe a star) whenever a cousin union occurs. That way you can see at a glance whether it’s a taboo spot or an allowed one. If you’re still stuck, just ask the elders—most of them can explain the code in a single sentence, and you’ll notice the pattern before you realize it’s a secret language.