Everyone should think about having an advanced health directive (australia) or it's equivalent.

Doctors cannot really accept informal documents regarding end of life. I know from bitter experience even clear lucid written statements of intent informally made by a dying person can be ignored by surgeons.

This stuff isn't scary, it's just sensible. The Australian one includes a declaration which can include or exclude the "daughter from california" in the decision process.

The process includes lawyers and doctors. There's an interactive web form from the government to guide you through.

I've done one. My partner has done one. We have no intention of needing it any time soon. We both feel better for having it.