Proof of POA. Any advice?

Do you believe that she does have it? It's a legal document, so a lawyer would have had to draw it up. Is there a family attorney? Can you call him or her? How often do you visit and pitch in? Can you assess the level of care your parent is getting?

This sibling should have sympathy, but she deserves sympathy from the rest of the family, too, since it sounds like she's doing all the work. It's incredibly hard to deal with dementia. She might be venting. She might be abusing your parent. It sounds like you don't have enough information or involvement to know what's really going on.

Have you ever taken care of an elder with dementia? Until and unless you've done so, for any considerable length of time, please do not pass judgement on your sibling who's likely exhausted and burned out to a crisp dealing with God-knows-what all with your parent! What you think is horrible is nothing at all compared to what your sibling is witnessing on a daily basis. You think this sibling should have a bit of sympathy, how about a bit of sympathy & empathy for this sibling who's doing the caregiving on YOUR part???? It is SOOO easy for the armchair critics to say what 'should be' going on with the people who are actually doing the hands-on caregiving in the trenches on a daily basis, it's unbelievable!

You should tell your sibling that once s/he lets you see the POA document, that you will happily & gladly take over ALL the care and management for your demented parent on a 24/7 basis. That should do the trick in getting your sibling to send you a copy of the POA document in short order.

PoA rules can vary by state. Here in MN where I live, my own elder law attorney told me that a PoA doesn't have to show anyone except a judge the documents. But, you can go to an elder law attorney to craft a letter informing your sibling that if they don't disclose the documents that you will take them to court to do it. And you must be ready to call this bluff and pay for the legal work.

Does your sibling live with your parent? If so, she could be burning out from the amount of care your parent needs. Dementia means that your parent may say do awful things all day long, with no remorse, since the disease robs them of their ability to empathize with others. It takes away their inhibitions, reason and logic. Which leaves a hot mess that drains the life out of their caregivers if they don't have enough support and breaks. Maybe ask your sibling if she needs help?