Like Bhavik says, she'll have to give her ok. You can get information from her to check the chart and information online, too. She'd have to give her password too.
Your sister has to put on the approved list and then let the doctors know that it's okay to talk to you. I don't foresee the doctors talking to every family member individually. If you're the only one, I'm sure they'd talk to you on the phone.
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