The siblings? I don't think so.
They are young and have their lives still ahead of them. They won't want to give up their livelihoods w/childern to care for Terri 24/7.
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They have already said they would.
Saying and actually doing are totally different. Right now, the sibs are trying to help the parents get their way.
Down the road, the sibs will see how their lives are consumed taking care of her.
Then they will want to pull her tubes/plugs.
I've seen similar cases and first intentions always are good.
Actual, hands on, is another thing.