Depending on what your goal is, and the level of trust between the two parties, setting up a Cold Card with a 2 of 3 between the two primary parties and a trusted third party (like your lawyer’s or accountant’s office with strict terms on the their conditions on coordinating access ie one of the two primary parties being legally dead or incapable of power of attorney) would accomplish the same thing. If I’m catching your drift. Anything less (like sharing the primary seed between both parties) would open up both to human factors and theft, especially if one of the parties has a vagina. Opinion only, I offer no legal, marriage, or investment advice.