I remember learning about Shamir’s secret sharing, and indeed the concept is fascinating. I’m not sure passwords is the best use case of something like that, but I’m not against it in theory. On the other hand, I have thought about breaking my master passphrase into several parts (word 1 + word 2, word 2 + word 3, word 3 + word 4, etc.) and giving each two word segment to my siblings. If all my siblings minus one got together, say in the event of my death, they would have my full master passphrase to get into all the things I have protected behind it.