> This method works because your mum is never going to go into conspiracy with your business partner to gain access to your information.

Unless your mom is Lucille Bluth.

I think a better way would be to have one person click 'Mark is dead' and it immediately sends an email to Mark saying 'Joe says you're dead.' If Mark doesnt' access the account within x days, then it sends further confirmation emails to Mom and business partner who also have to confirm that Mark is dead. If so, then it set 'Mark = dead' and opens the vaults as Mark configured.