Looks very cool. The short story has a small problem, though. From reading it, it is unclear that the writer is looking for a 2/2 multisig scheme. From my context (marriage), a shared account is a 1/2 multisig, which can be implemented in a much simpler way: sharing a private key.
(I also added a comment there: https://medium.com/@israel_69007/while-multisig-accounts-are-a-very-useful-thing-many-shared-accounts-work-on-a-1-x-scheme-meaning-bc02fa2ef91a)
This, of course, does not detract from the importance or utility of other, more sophisticated multisigs. Thanks and KUTGW.