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A Non-durable POA is only valid after the person passes.
If I'm wrong, someone please kindly correct me.
So, if you and your one sister have a durable POA, sister cannot do anything to block the move to Memory Care.
One POA is giving permission for someone to handle something for you one time. Like a sale of property. Once the property is sold, the POA is no longer in effect.
DPOA is assigned by Principle. Some are immediate upon signing others are "spring" meaning the principle has to be incompetent for it to become valid. My Moms read if she was found no longer competent.