Funny and stupid thing about that. When we bought our Model S in 2015, we had both my name and my wife's name on the registration. It's important to note that back in 2015, you accepted your car by signing physical documents, nothing was electronic.
We tried to do the same joint registration for our Model X in 2021...we thought it would Just Work, but it turned out that at delivery time (2022q1), the system was expecting her to accept purchase terms with the app logged into her MyTesla account. It turns out that a MyTesla account was created for her back in 2015, but we didn't know about it. So we had to try to password reset her account so she could login, but there was some other snafu, so we ended up finishing the paperwork with wet signatures on hardcopy. (All a few hours before EOQ, clock ticking down, etc.)
I have no idea what account her app is logged into right now...guess I'd better figure that out before she tries to drive the car.
It feels to me there's some lesson to be learned here but I'm not sure what.
Bruce.