I just discussed with my husband how we all need living wills so that we will never put our loved ones at one another's throats like this, trying to read our minds. This could happen even when everyone involved is truly interested in the very best for the comatose person.We have them. In Wisconsin, they're called "durable power of attorney for health care."
I got into a huge fight with one of my sisters who me she was going to be the one to make the decision concerning my father, that it'd be her decision "to pull the plug." I told her that if she even thought about it, especially because he was competent enough to make his own decisions at the time she told me--and continued to be competent until he died--that if she tried to pull anything like that, I would sue the living crap out of her. It was very divisive in the family.
I had no opinion on whether to use extraordinary measures or not to use extraordinary measures. It was my father's life and it was his choice, and I'd support the decision he made. Ultimately, he decided on no extraordinary measures and died in his own bed, like he wanted.
My Mom asked that every effort be made to revive her should she be unable to speak for herself. I honored that wish through coma and two cardiac arrests when it was becoming more and more obvious that she wasn't coming back. I had to decided when enough was enough. I was on the way to the hospital to reluctantly put in a DNR (Do Not Recuscitate) order when they paged me and said her vitals had changed. When I got there I found out that that meant she had died.
The point is that the medical people were always after her, when she was alert, to put a DNR on herself. They wanted to kill her. She had no value to them. She recovered fully several times over the last five years of her life in spite of the crepe-hanging medical people.