This is a challenge and one that I've just been through. As an 80 yo I'm doing some planning before the big day arrives. I'm not afraid of dying, I just don't want to be there at the time!
SWMBO has always had a credit card as a subset of mine. So we set out to get her one in her own name. Filled out all the paperwork and after being requested to send the bank a copy of our account statement that they sent to me (go figure!) we got into a conversation with the bank on the details. Once I was identified as being in on the conversation I was asked to leave as it was none of my business (really?) so I sat quietly listening. As the conversation went on it became obvious that the person on the other end had no idea how 57 year marriages and joint accounts and joint family SMSF's work so I jumped in and said...."Look, I'm dying and I want to get this sorted out before I go!" Oh, please hold for a moment............30 secs later, "Yes, that's been approved and the authorizsation email is on it's way". Job done. I didn't lie - I'm dying, just don't know when at the moment. By the way...NAB.
Good luck with your challenge.