My sister has POA for healthcare and refuses to allow other siblings to even know their condition. Does she not have to tell us?

Fluffysmom22, could you give us more information. Such as who are "their" and "both"? Are you referring to your parents?

It could be that your sister is exhausted being Power of Attorney as at times it feels like having a full-time job and more so when there is a serious health condition which requires Rehab, etc.

Sounds like you and the siblings are not able to visit, correct? Or be able to offer to help your sibling who is the POA?

Well, I don't think she "has" to tell you, but it would seem the logical thing to do in a functional family.

What reason does she give for not communicating this information? What do you think is the real reason?

Are siblings near enough to make visits and see for yourselves?